AIX is short for Advanced Interactive eXecutive. AIX is the UNIX operating system from IBM for RS/6000, pSeries and the latest p5 & p5+ systems. Currently, it is called "System P". AIX/5L the 5L addition to AIX stands for version 5 and Linux affinity. AIX and RS/6000 was released on the 14th of February, 1990 in London. Currently, the latest release of AIX is version 6. AIX 7 beta will be released in Aug 2010, along with the new POWER7 hardware range.
Multi-platform UNIX systems consultant and administrator in mutualized and virtualized environments
I have 4.5+ years experience in AIX system Administration field. This site will be helpful for system administrator in their day to day activities.Your comments on posts are welcome.This blog is all about IBM AIX Unix flavour. This blog will be used by System admins who will be using AIX in their work life. It can also be used for those newbies who want to get certifications in AIX Administration. This blog will be updated frequently to help the system admins and other new learners. DISCLAIMER: Please note that blog owner takes no responsibility of any kind for any type of data loss or damage by trying any of the command/method mentioned in this blog. You may use the commands/method/scripts on your own responsibility.
If you find something useful, a comment would be appreciated to let other viewers also know that the solution/method work(ed) for you.
Q. To show which filesets need to be installed or corrected ?
A. lppchk -v
Q. how to fix if a vg is corrupted?
A. for rootvg use redefinevg -d hdisk0 rootvg
For non-roorvg use import and export
For PV use syncvg -p hdisk2 hdisk3
To all PV in VG use syncvg -v testvg
For LV use reorgvg testvg lv1 lv2
For FS use fsck -y /dev/lvname
Q. How to replace a disk?
A. extendvg testvg
migratepv
reducevg -d testvg
Q. How can I clone the rootvg?
A. alt_disk_copy -d hdisk1
(from 5.3 onwards alt_disk_install is devided into alt_disk_copy, alt_disk_mksysb and alt_disk_op )
Q. How many processors does my system have?
A. lscfg |grep proc
bindprocessor -q
lsdev -Cc processor
Q. How can I determine which fileset updates are missing from 6100-10 ?
A. #oslevel -rl 6100-10
Q. How do I mount a cd?
A. mount -v cdrfs -o rw /dev/cd0 /cdrom
Q. How do I display information about installed filesets on my system?
A. #lslpp -l
Q. How to check whether the APAR is installed or not ?
A. #instfix -ik ( here apar's are started with IV , IZ & IY73748)
Q. How to set non-expiry password in AIX?
A. #pwdadm -C
Q. What is /etc/inittab?
A. It contains the startup sequence of all processes, fields are PID,Runlevel,Action and command
Q. What is the first process to start on a UNIX system, after the kernel?
A. init
Q. What is an inode?
A. i-node (index node) A file system has a fixed number of i-nodes that are located following the superblock. i-nodes contain information about files, including the location of the data on the disk. They contain all of the identifying information about files (file type, size, permissions, user/group/owner, create/modification and last access dates) except for the file name, which is stored in the directory, and the contents of the file, which are stored in the data blocks. Each file or directory has an i-node associated with it. AIX reserves a number of i-nodes for files and directories every time a file system is created, and if all the available inodes are used, no more files can be created, even if the fs has free space.
Q. What is super block ? how to recover superblock ?
A. Superblock In a JFS, the superblock is the first addressable block (and a backup at the thirty-first addressable block) on a file system. It is 4096 bytes in size. The superblock is very important because a file system cannot be mounted if the superblock is corrupted. This is why there is a secondary or backup superblock at block 31. The superblock contains the following: size of the filesystem, number of datablocks in the fs, state of the fs...
Q. What is the Changed time on an inode/file mean?
A. Last time the inode was modified
Q. What’s an indirect block?
A. Pointer to a list of blocks
Q. What is RAID?
A. Redundant Array of Independant Disks, striping, mirroring, and Stripping with parity etc..
Q. How do I change the priority of a process?
A. renice -n 5 -p
nice -n 15 WE can use from 0-39
The nice command runs another command at a different priority, while the renice command changes the priority of an already running process
Q. How do u find the fix is installed? A. Lslpp -l
instfix -i| grep ML
Q. Attributes of FS? A. File size, date,owner,name etc.....
##Q. List all the LV in system? A. lslv -L
Q. Why is the . not included in the path ?
A. the dot is not supposed to be in your path because when you enter a command, your environment i.e. your path will try and execute from your pwd which is never a good thing.
Q. A system is echoing the ping but not able to login via telnet why ? A. edit /etc /services & /etc/inetd.conf
Telnet daemon is down and telnet service is not active
Q. How to migrate 5.3 to 6.1 ? (or any versions) A. Migration insttalation using NIM or AIX CD.
Q. A system is able to ping within the network but not outside why ? A. default gateway is not defined or not cofigured properly
Q. What are the components of a HACMP ? (did you use serial interface) A. - Nodes
- Networks
- Sites
- Topology
- Resource Groups
- RSCT components (group services, topology services and RMC)
- Events and Notifications
- Recovery scripts
Q. How to Upgrade a cluster, if you have deployed PowerHA SystemMirror 7.1 or Cluster Aware AIX in your AIX environment ?
A. If you are using PowerHA SystemMirror 7.1:
1. Backup the cluster configuration using the PowerHA SystemMirror snapshot facility
2. Stop the PowerHA 7.1.0 Cluster Services through SMIT. Select the entire list of nodes names to stop cluster services on all nodes in the cluster: (smitty hacmp -> System Management(CSPOC) -> PowerHA System Mirror Services -> Stop Cluster Services).
3. Remove the CAA cluster using the AIX command rmcluster (syntax: rmcluster –n clusterName) on one of the nodes in the cluster.
4. Install the desired AIX Level (6100-07 or 7100-01 or later AIX Technology Level) on all nodes. Note that this step will also install the latest level of RSCT.
5. Note that reboot would be necessary after the update of the AIX TL level.
6. Verify to make sure that the AIX and RSCT levels are the following:
a. AIX 6100-07 or 7100-01 or higher
b. RSCT Level 3.1.2.0 or higher
7. Recreate the CAA cluster from PowerHA SystemMirror: (smitty hacmp -> Cluster Nodes and Networks -> Verify and Synchronize the cluster configuration)
8. Restart the PowerHA SystemMirror 7.1 Cluster: (smitty hacmp -> System Management (CSPOC) -> PowerHA System Mirror Services -> Start Cluster Services).
If you are using Cluster Aware AIX:
1. Note down the CAA cluster configuration information.
2. Remove the CAA cluster using the AIX command rmcluster.
3. Install the desired 2011 AIX Technology Level (6100-07/7100-01) or later AIX
releases on all nodes. Reboot the node as necessary.
4. Redeploy the CAA cluster using mkcluster command.
Q. What are the resource groups in HACMP? A. Rotating, cascading and mutual takeover
Q. What are the apar install if so for what ? A. Apar is interim fix for fixing identified issues between the release of various SP levels. SP level is often consists of collection of various apars.
check for installed apar using command "instfix -ik
Q. How will you log in or start the system if u don't know the root password? A. boot in maintanance mode and set the root password
Q. What is ip address and subnet means ? A. internet protocol address is used to communicate wit other devices in the network, subnet mask is used to identify the network address of an ip address
Q. how will you check, if a system is paging excessively ? A. check the configured paging space and its usage using command "lsps -a"
- Check the the snapshot of system resource usage using command "topaS"
- check detailed paging space utilization using command "vmstat"
Q. There is too much of processor utilization what could be possible reason? A. too much processor utilization could be because of defunct processes, respawning process and high processor utilizing applications.
Q. How is paging space is allocated? A. It is allocated in form of a paging LV configured either on a rootvg, secondary devices or both
Q. How will you assign superuser privilege to an ordinary user temporarily (sudo) A. RBAC is introduced in AIX 6.1
Q. Based on what one will choose to use shell or perl scripting ? A.Some complex functions cannot be executed with generic shell so a special program code is used in another language which could be perl.
Q. Difference between telnet or ssh . A. ssh is secure shell using a secure shell protocol where as telnet provides unsecured communication
ssh could be configured as a server/client, but it is not possible with telnet
Q. How will you truncate a log file ?
A. To truncate a file we need to be nullify that means #cp /dev/null
What is a sticky bit what is the effect on file and directory ?
A. Stickybit is used set the permissions of a user. If u set sticky bit then that user and the super user only can rename and delete the file or dir
chmod +t To add sticky bit
chmod -t To remove sticky bit
chmod g+s to set SGID
chmod u+s To set SUID
Q. How to check Broken filesets?
A. lppchk -v
Q. What is ur ticketing agent?
A.Maximo
Q. How to check all FS’s in a vg?
A. lsvg –l
##Q.How to find Which LV is mapped to which PV?
A. lslv –m
Q. Which LV is not mounted at the system boot?
A. boot , paging , raw
##Q. What is the extension for snapshot?how to take snapshot?
ftp testcase.software.ibm.com login as user 'anonymous' with your email address for the password
ftp> cd /toibm/aix ftp> bin ftp> hash ftp> put pmr#.branch#.000.snap.pax.Z ftp> bye
Q. How to change the priority of the process?
A. nice -- command
Q. How to check Errors ?
A. Using alog and errpt (errpt –a –j For detaild view )
Q. How to install a fix and a software?
A. instfix and installp
Instfix – to install the fixes that extension with IZ (IX38794) ; instfix –k -d
Installp – to install the filesets
Emgr –P –e (For preview)
Emgr –X –e (for installation)
--> Q. How to clear the failed filesets?
A. lslpp –C
Q. How to replace physical volume in hacmp? (From sharedvg while online)
First take the backup of that disk and inform to all client, which are login by server.
Use smitty hacmp -> C-SPOC -> HACMP physical volume management -> Add a source disk -> add a destination disk.
Q. How will you replace falling disk mirrored rootvg?
unmirrorvg rootvg diskname
chpv –c faileddiskname
reducevg rootvg diskname
rmdev –dl diskname
Add new disk and configure using cfgmgr
extendvg rootvg diskname
mirrorvg rootvg diskname
syncvg –v rootvg
bosboot –ad /dev/diskname
Set bootlist
Q. Difference between AIX5.1, 5.2 and 5.3?
AIX 5.1 Jfs2 file system is introduced
Support both uni and multiprocessor.
AIX 5.2 DLPAR
System scalablity
Jfs2 file system upto 16TB
DuoD-Dyanamic capacity upgrade on demand
AIX5.3 Scalable vg introduced
Support only multiprocessor kernel
DLPAR
Workload management
Variable Logical Track Group size
Shrink file system support
Dump procedure is enhanced to use nvram to store minimal dump info.
AIX 6.1 turning off jfs2 logging to increase performance
rm command & variable LTG(Logical Track Group)
new security enhancements & OS is installed with minimal services, allowing you to activate only the additional features that you actually need
RBAC is added
WPAR
Enhanced Virtualization,Live Partition mobility
Q. What is the stanza of lsvg –l rootvg?
Lvname, type, lp, pp, pv, lvstate, mount point
Q. What is the procedure to configure LPAR?
Typically all partition creation and management is performed through the H/W(HMC). The CLI is an advanced option and still requires an HMC.
TASK No Description Comment.
Start the partition wizard
Partition name ID and type
Workload management participation
Partition profile name
Partition profile memory values
Partition profile processor value
Partition profile interactive value (if available)
Allocation of physical I/O resources
Allocation of virtual I/O resources.
Q. What is the stanza of /etc/security/login.cfg?
It contained parameter related login info like logintimes,loginreenable, logindelay, logindiabled etc.
Q. What is /etc/security/limit?
It contained resource limit a user can use. Resources like no of CPU, amount of RAM, size of file etc.
Q. What are the major problems you are attended In your setup?
Generally I faced file system full, performace problem, booting problem, and network problem, disk failure, Ethernet adapter failure, memory problem, and loose connection of cables.
Q. If the user login, the system is very slow, what steps you will follow?
Entry is available in /etc/nologin for that user, root should remove this entry then only user can login.
Q. What is the snap and its. Output directory?
Snap is used to format dump o/p and send to IBM. /tmp/ibmsupt/genral
Q. In production environment what is the procedure to down the application?
Inform team leader and IT head and take permission. Inform all users to logout, who is login.
We used in commercial tax
First shutdown report server by stopping service
Second shutdown application server by stopping service.
Then shutdown oracle database server then if necessary power of all machine.
Q. umask value for security references?
022
Q. How to change the PP size, which already exists VG? Is it possible? Tell the procedure?
Change pp size by opening vi /image.data
Create mksysb using I option
Then restore mksysb
Q. If user complaint that the system is very slow, what step you will follow?
Check where the system resources is overloaded by performance tool.
Kill that process, which are using more resources with the consultation with team leader & IT head. And inform all the users who is login?
Q. how to find the selected device is bootable or not?
A. ipl_varyon -i
Q.How to check the processor type?
lsattr -El proc0 -a type
lscfg -vps -l proc0
Q.is a non-root user needs to be able to create users, change passwords ?
In AIX 5.3, RBAC (Role Based Access Control) is not available. It's available only from AIX 6.1.
Q. How to Move all LV's in a PV which was damaged?
Q. How to check the power supply is hot swappable or not?
#lsslot
Q. How would I know if my System p machine (hardware) is 32-bit or 64-bit?
bootinfo -y
Q. How much real memory does my machine have?
bootinfo -r & lsattr -El sys0 -a realmem
Q. How do I get a detailed configuration of my system?lscfg -vl rmt0Q. What version, release, and maintenance level of AIX is running on my system?oslevel -r & lslpp -h bos.rte
Q. How can I determine which fileset updates are missing from a particular AIX level 5300-04?oslevel -rl 5300-04Q. What SP (Service Pack) is installed on my system?oslevel -sQ. How do I install an individual fix by APAR from cd?instfix -k IY73748 -d /dev/cd0 Q. How do I verify if filesets have required prerequisites and are completely installed?lppchk -v
Q. How do I enable or disable SMT?smtctl [ -m off | on] [ -w boot | now]Q. How do I get partition-specific information and statistics?lparstatQ. How do I know if my volume group is normal, big, or scalable?Run the lsvg command on the volume group and look at the value for MAX PVs. The value is 32 for normal, 128 for big, and 1024 for scalable volume group.
Q. How do I mirror a logical volume?
mklvcopy LogicalVolumeName Numberofcopies
syncvg VolumeGroupName
Q. How do I remove a copy of a logical volume?rmlvcopy testlv
Q. How do I find out what the maximum supported logical track group (LTG) size of my HDD?
#/usr/sbin/lquerypv -M hdisk0
Q. How can I clone (make a copy of ) the rootvg?
alt_disk_copy -d hdisk1
Q. How can u change IP of one node in HACMP environment ?
A- SMIT TCP/IP
Q. How to fix if a external storage is visible to one node and not to other node in HACMP?
A- Using chdev command I will make PVID=yes and command is chdev -l hdiskn -a PV=yes
Q. How can u increase file system size in HACMP ?
A- Through C-SPOC
Q. How to Fix if a VG is not Available in ODM?
A- smit importvg
Q. What is heart beat in HACMP ?
A-heartbeat is used for health monitoring of nodes(whether or not nodes are alive)
Q. What are the basic requirement for two nodes to be configured in HACMP?
A-each node should have 2 NICs, hardware should be same and OS and ML must be same
Q. how to check whether a node is in cluster ?
A- using ./clstat
Q. What is the daemon for HACMP?
A- clstrmgrES, clsmuxpdES,clinfoES and clcomdES
Q. What are the permissions in AIX ?
A- read, write,execute ,SUID,SGID, Sticky bit
Q. How to give all permission, only to user of a file ?
Q. What is NFS and which daemon it is using, what is configuration files?
Ans. NFS is network file system which use for sharing file on the linux/unix plateform.
Server side daemons are- nfsd, rpc.mountd, rpc.statd, portmap
Client side daemons are- biod, rpc.statd, portmap
Q. What is portmap?
Ans. It provide port no for client request
Q. How to increase filesystem size?
Ans. Chfs –a +size= m,g /filesystem
Q. What is difference between RAID 0 and RAID 1?
Ans Raid 0 is used for striping purpose and Raid 1 is using for mirroring.
Q. What is swapon and swapoff command?
Ans Swapon turn on paging space and swapoff used to turnoff paging space
Q. What is mksysb?
Ans It’s a command which used to take backup of rootvg
Q. What is difference between jfs and jfs2?
Ans jfs jfs2
1-Inode size 128 Byte 512Byte
2-Max file size 64GB 4PB
3-Max filesystem size 1TB 4PB
4-Compresion yes no
5-jfslog-type General jfslog inline-jfslog
Minimum file system size not specify 16MB
Inode allocation static dynamic
Q. How to start mountd daemon?
Ans startsrc –s mountd
Q. Which is the ODM command to list the ODM object that stores the PVID?
Ans. odmget -q name=hdisk0 CuAt
Q. What are the basic components of ODM and in which format data is stored in ODM.
Ans. Components are uniquetype, attribute, deflt and values. Data is stored in binary format
Q. Which is the environment variable used by all the ODM commands?And that is set in file/etc/environment. What is its default value. [2 marks]
Ans. ODMDIR and default value is /etc/objrepos
Q. Which three types of information are not managed by ODM? [1/1/2]
Ans. Filesystem information, User/Security information, Queues and Queue devices.
Q. Which repositories stores the ODM object classes? [1/1/2]
Ans. /etc/objrepos, /usr/lib/objrepos and /usr/share/lib/objrepos
Q. Which is the ODM object class used by cfgmgr to determine the correct sequence when configuring devices. [1/2 mark]
Ans. Config_Rules
Q. What are the contents of Boot Logical Volume? Briefly explain them? [2 marks]
Ans. AIX Kernel, rc.boot, Reduced ODM and Boot commands.
AIX kernel – It is always loaded from the boot logical volume. It provides basic services like process, memory and device management.
Rc.boot – after starting the kernel, the boot script rc.boot gets control over the boot process.
Reduced copy of ODM – During the boot process many devices are configured before hd4 is available. For these devices the corresponding ODM files must be stored in the boot logical volume.
Boot commands – The boot commands are programs that are called during the boot process eg. Bootinfo, cfgmgr.
Q. How to fix a corrupted BLV by using a CD or tape? [2 marks]
Ans. Boot the machine in maintenance mode from a CD or tape.
Access rootvg.
Run command bosboot –ad /dev/hdiskn
Use savebase command
Use command Shutdown –Fr so that all changes are written from memory to disk.
Q. List the sequence in which the default boot list in RS/6000 is stored? [2 marks]
Ans. 1. Diskette Drive
2. CD-ROM
3. Internal disk
4. Communication adapter (like Ethernet or token-ring)
Q. The diag command is part of which package?
Ans. bos.rte.diag [1/2 mark]
Q. How will you change bootlist for PCI & classical system (MCA) ?
Ans. # bootlist -m normal hdisk1 hdisk0
On some PCI systems (like 43p) bootlist cannot be changed using the bootlist command. For such systems , we have to change the bootlist using System Management Services (SMS) menu by pressing F5/F6 key at the time of system boot.
Q. How do you start & stop a subsystem & susbsystem group like inetd and tcpip.
Ans. # startsrc -g tcpip --> for starting a group of services
# startsrc -s inetd --> for starting a single service.
Q. What are the packages to be installed for man pages & networking?
Ans. bos.info and bos.net
Q. How do you remove an installed package?
Ans. # installp –u –f listfile
Q. What is the use of mkszfile?
Ans. Saves the system state for reinstallation on the current system or another system. The mkszfile command overwrites an existing /image.data file with new information.
Q. Write down the command for checking bootlog?
Ans. # alog -o -t boot
Q. How do you change the run level from single user mode to multiuser mode?
Ans. # telinit 2
Q. Write down the command syntax for listing all supported and customized devices?
Ans. $ lsdev -C –H --> lists all customized devices with header
$ lsdev -P –H --> lists all supported devices.
Q. Write the command for checking the amount of memory for PCI and CLASSICAL RS6000?
Q. Write the command for changing maximum number of user process from 40 to 80?
Ans. # chdev -l sys0 -a maxuproc=80
Q. How do you configure a defined device?
Ans. # mkdev -l devname
Q. Write down the command for disabling tty0?
Ans. # chdev –l ‘tty0’ –a login=’disable’
Q. Can one printer belongs to multiple queues? If yes then when do you use this and if no why it's not possible?
Ans. Yes . We use this when the same printer is used under different emulation like – post script , PCL emulation ,ASCII , etc. We can add different queues for different emulation.
Q. Can you configure a queue to multiple printers (y/n)?If yes then write the print command to a queue on a specific printer? If no write down the reason.
Ans. Yes, $ lpr –P lp0:
Q. What is the command syntax for testing queue status?
Ans. $ lpstat –t
Q. Where does the information about queues and printer stored?
Ans. /etc/qconfig
Q. Write down the command syntax for changing the priorities of a print job?
Ans. # qpri - # JobNumber -a PriorityNumber
The job number and priority number can be obtained by running the lpstat –t command. The priority can only be changed by printer administrator or system administrator.
Q. Write down commands syntax for listing all VG and content of a single vg?
Ans. $ lsvg --> lists all volume groups.
$ lsvg –o --> lists only active volume groups.
$ lsvg --> displays characteristics of volume group.
$ lsvg –l --> logical volumes
$ lsvg –p --> physical volumes
Q. Write down the command to find out which PV belongs to which VG?
Ans. $ lspv
Q. Write down command for making a volume group ?
Ans. # mkvg -s –y
-B flag may be used for creating big volume group ( maxpvs. 128)
-t is used for specifying the PP size.
Q. What is the command for synchronizing a logical volume copy (mirror)?
Ans. # syncvg here name could be VG , PV or a LV name.
Q. Write down the command for turning off a mirroring of a logical volume ?
Ans. # rmlvcopy
Q. Can you define different Quotas on different filesystems for a single user?
Ans. Yes.
Q. How to go to parent directory ?
Ans. $ cd ..
Q. How to execute .profile without logging in again ?
Ans. $ sh .profile
Q. How to debug shell script ?
Ans. $ sh -x shellfile.
Q. What is first line in shell script
Ans. #!/usr/bin/ksh - path to the shell but no comments. ! is important.
Q. If you are not able to telnet what are the possible reasons and how to diagnose it ?
Ans. The possible reasons are:
1. Network connection not through.
2. Wrong IP address.
3. Client not in the same network.
4. Telnet disabled on the server.edit /etc/inetd.conf
5.check /etc/hosts.allow or /etc/hosts.deny in Ur system, then rename it.
The problem could be diagnosed using 1.) ping 2.) ifconfig 3.) netstat –v 4.) traceroute
Q. What is the entry in resolv.conf for DNS client ?.
Ans. Domain abc.aus.century.com
nameserver 192.9.209.1
nameserver 192.10.25.5
Q. How to extend lv ?
Ans. # extendlv
Q. What is echo $$ ?
Ans. Returns current shell’s PID
Q. How to unmount a filesystem and if it is not able to unmount what are the steps ?
Ans. # umount
Q. How to take the backup of a dump?
Ans. # snap -a -o
-a Gathers all system configuration information. This option requires approximately 8MB of temporary disk space.
-o OutputDevice Copies the compressed image onto diskette or tape.
Q. How to extend the File systems size ?
Ans. # chfs -a size=Newsize filesystem
-a size=NewSize Specifies the size of the Enhanced Journaled File System in 512-byte blocks. If Value begins with a +, it is interpreted as a request to increase the file system size by the specified amount.
Q. How to see the routing table ?
Ans. $ netstat –rn
-n Shows network addresses as numbers & -r Shows the routing tables
Q. How to see the arp cache ?
Ans. $ arp -a
Q. What are the daemons for NFS Primary server ?
Ans. nfsd, bind,rpc.statd, portmap
Q. What are the daemons for NIS(Network Information Service) ?
Ans. ypbind, ypserv, yppasswd, portmap
Q. How to access the NFS mounted File System ?
Ans. Just go to the Directory or Access the directory under the filesystem
Q. What is automount ? ( explain briefly )
Ans. a) Used for automatic and transparent mounting and unmounting of NFS File systems.
Based on AutoFS facility.
Uses automounter map files to find the mount directories and mount arguments. Map can be text files or NIS maps.
automount command
automountd daemon
Client-side server
Benefits:
Reduces system administration of /etc/filesystems file particularly if NIS maps are used
No pre-mounting of directories not currently needed thus reducing possibility of client hang due to down server
Distributes client workload for NFS read-only file systems
Provides method for single-system image for clients
-l Lists the current value of the primary and secondary dump devices, copy directory, and forcecopy attribute.
Q. How to see memory activity ?
Ans. Using "sar", "vmstat"
Q. How to install software ?
Ans. # installp –a –Q –d -f ‘all latest’
-a Applies one or more software products or updates.
-d Device Specifies where the installation media can be found.
-f ListFile Reads the names of the software products from ListFile.
Q. "no" command options especially 'thewall' parameter.
Ans. Network option Configures network attributes.
no { -a | -d Attribute | -o Attribute [ =NewValue ] }
thewall Specifies the maximum amount of memory, in kilobytes, that is allocated to the memory pool. In AIX 4.2.1 and earlier, the default value is 1/8 of real memory or 65536 (64 megabytes), whichever is smaller. In AIX 4.3, the default value is 1/8 of real memory or 131072 (128 megabytes), whichever is smaller. In AIX 4.3.1, the default value is 1/2 of real memory or 131072 (128 megabytes), whichever is smaller. In AIX 4.3.2 and later, the default value depends on whether you are running on a CHRP machine or not. For non-CHRP machines, the default value is 1/2 of real memory or 262144 (256 megabytes), whichever is smaller. For CHRP machines, the default value is 1/2 of real memory or 1048576 (1 gigabyte). thewall is a runtime attribute.
Q. ODM - where it resides, how to modify,list,etc.,
Ans. ODM resides in /etc/objrepos , /usr/lib/objrepos and /usr/share/lib/objrepos.
To modify ODM use the following sequence :
# odmget -q"uniquetype=tape/scsi/8mm and attribute=block_size" PdAt > file
# vi file edit the corresponding attribute.
# odmdelete -o PdAt -q"uniquetype=tape/scsi/8mm and attribute=block_size"
# odmadd file
To list contents of ODM use lsdev command.
Q. File systems - nbpi, etc., read the theory.
Ans. nbpi – number of bytes per inode.
This feature of filesystem is used when fragmentation of files are set. If a filesystem contains small files , then it is advantageous to keep the fragment size small , so that space is not wasted. Normally there is one inode created for every possible file in a filesystem. However in actual practice the number of inodes required are quite less. Therefore to save on space allocated for inodes , we specify the nbpi value.
Q. How do I setup anonymous ftp on my AIX system?
Ans. /usr/lpp/tcpip/samples/anon.ftp It is a shell script and will set up a anonymous ftp site on your local RS/6000.
Q. How can I share files/printers with Windows 95?
Ans. The freeware solution is Samba .Commercial solutions include Fusion95 from Performance Technology
Q. How do I shrink /usr?
Ans. 1) Remove any unneeded files from /usr.
2) Make sure all filesystems in the root volume group are mounted. If not, they will not be included in the re-installed system.
3) Type mkszfile. This will create /image.data that contains a list of the active filesystems in the root volume group that will be included in the installation procedure.
4) Edit /image.data. Change the size of /usr to what you want.
IMPORTANT: Make sure that you Don't enter a value which is less than the size of the FS required to contain the current data. Doing so will cause the re-installation procedure to fail.
5) chdev -l rmt0 -a block=512 -T
6) Unmount all filesystems that are NOT in the root volume group.
7) Varyoff all user-defined volume groups, if any # varyoffvg VGname
8) Export the user-defined volume groups, if any # exportvg VGname
9) With a tape in the tape drive, type # mksysb /dev/rmt0
This will do a complete system backup, which will include information (in the /image.data file) for the installation procedure on how large the filesystems are to be created.
10) Install the backup .
11) When the installation is complete, you may then import any user-defined volume groups.
# importvg -y VGname PVname
where "VGname" is the name of the volume group, and "PVname" is the name of any one of the physical volumes in the volume group.
12) Varyon your user-defined volume groups
# varyonvg VGname
The reduction of the filesystems is now complete.
Q. What is LVCB ?
Ans. The logical volume control block (lvcb) is the first 512 bytes of a logical volume. This area holds important information such as the creation date of the logical volume,
information about mirrored copies, and possible mount points in a journaled filesystem.
Q. What is the limit on Physical Partitions Per Volume Group?
Ans. 1016 Physical Partitions Per Disk in a Volume Group
In most cases, not all the possible 1016 tracking partitions are used by a disk.
The default size of each Physical Partition during a "mkvg" command is 4 MB, which implies that individual disks up to 4 GB can be included into a volume group.
If a disk larger than 4 GB is added to a VG (based on usage of the default 4 MB size for PP) the disk addition will fail with a warning message that the PP size needs to be increased.* There are two instances where this limitation will be enforced. The first case is when the user tries to use "mkvg" to create a VG where the number of PP 's on one of the disks in the VG would exceed 1016. In this case, the user must pick from the available PP ranges of: 1, 2, (4), 8, 16, 32, 64, 128, 256, 512 or 1024 MB and use the "-s" option to "mkvg". The second case is where the disk which violates the 1016 limitation is attempting to join a pre-existing VG with the "extendvg" command. The user can either recreate the volume group with a larger PP size (which will allow the new disk to work with the 1016 limitation) or the user can create a standalone VG (consisting of a larger PP size) for the new disk.
Q. Why am I having trouble adding another disk to my VG?
Ans. a.) Not enough space left in the volume group descriptor area.(VGDA)
b.) Volume group can have a maximum of 32 disks in a volume group. ( 128 for big VG)
Q. How do I fix Volume Group Locked?
Ans. Use # (putlvodm -K `getlvodm -v ) #chvg -u
Q. How do I remove a volume group with no disks?
Ans. Without disks VG can't be live.
Q. How do I get rid of a disk that is no longer really in the volume group?
Ans. # reducevg -d -f
or if the hdname can't be found:
# reducevg -d -f
Q. What are the theoritical limits within the LVM?
Ans. The system may have 1 to 255 Volumes Groups (VG's).
Each VG may contain 1 to 32 Physical Volumes (PV's).
Each PV may contain upto 1016 Physical Partitions (PP's).
Each PP may have a size (square of 2) from 1 to 256MB (1024MB for AIX 4.3).
The filesystem and file limits are :
File jfs-Filesystem
3.2.5 2 GB 2 GB
4.1.x 2 GB 1 TB
4.2 64GB 1 TB
4.3 64 GB 1 TB
5.x 1 Tb 4 PB
6.x 4 PB 4 PB
Q. How do I control how hostnames are resolved?
Ans. The default order can be overwritten by creating the configuration file, /etc/netsvc.conf and specifying the desired order. Both the default and /etc/netsvc.conf can be overwritten with the environment variable, NSORDER.
Q. dtlogin ignores .profile?
Ans. Edit .dtprofile and remove # from the last line containing DTSOURCEPROFILE=true.
Q. How do I transfer files between AIX and DOS disks?
Ans. Install the AIX package bos.dosutils which has commands for transferring files between DOS diskettes and AIX. The commands are dosread, doswrite, dosdir, dosdel,
and dosformat.
Q. How do I determine the clock frequency of a RS/6000 by software ?
Ans. There is no way to find out the clock frequency with a piece of software
VERY IMPORTANT
1. What are your daily activities?
Ans. My daily activities include the following tasks:
1. To backup mksysb.
2. To work on LVM e.g. File system management.
3. To apply patches using instfix and emgr commands.
4. To manage daemons (Whether the daemons are working or not. If not working then to restart those daemons.). I get to know about these through Incident Management tickets.
5. Performance Monitoring using common AIX tools like sar, vmstat and iostat and ps.
6. Looking at errors using errpt command.
7. Creating LPARs, though its not very occasional activity.
8. Dynamic resource management among LPARs using DLPAR.
9. Client installation using NIM.
2. How AIX is different from other Unix Operating systems ..?
Ans : LV M Concepts ( Policies …where you can optimize the performance )
ODM
Dynamic Kernel
Auto Configuration of devices (cfgmgr)
Dynamic increasing of file system
JFS & JFS Log..Prevents the file system corruption.
Booting from alternate Disk
Rootvg Cloning
3. How to install oracle on linux? What are the prerequisites to install oracle ?
Ans : Need to set kernel parameters, install necessary fixes, create required users and groups, set path and profile, exact installation procedure comes documented with oracle installation media.
4. How to u find the system is I/O bound
Ans : If the iowait value is more in the iostat output system can say I/O bound provided the disk balance are good.
5. How u find system is memory bound?
Ans : By observing the pi&po field in vmstat Output
6. How to see user resource limit
Ans : ulimit –a
7. Boot Process of AIX?
Ans : Post
Locate the blv using bootlist
Load the blv and pass control
Configure the device through cfgmgr
Start init and process /etc/inittab
8. How to recreate BLV?
Ans :Got on SMS mode – access rootvg with mounting then #bosbot –ad /dev/hdisk0 #shutdown –Fr
9.How to change the maintenance mode?
Ans : Init m
10.How to reset lost password of root?
Ans : Go to SMS mode – access rootvg with mounting then #passwd then #shutdown –Fr
Device
What is the stage of cfgmgr?
Ans : 1.Check predefined database. 2.Load device driver from odm and made entry on /dev directory
And 3.Put the entry in customized devices database.
Write the command for changing maximum number of user process from 40 to 80?
Ans. # chdev -l sys0 -a maxuproc=80
How do you configure a defined device?
Ans. # mkdev -l devname
Write down the command for disabling tty0?
Ans. # chdev –l ‘tty0’ –a login=’disable’
How to make available disk to PV.
Ans: #chdev -l hdisk1 - a pv=yes
How to use chdev ..command … to change the block size of tape
Ans : chdev -l rmt0 block_size=1024
How to see the default attributes of tape or system
Ans : lsattr -E -l rmt0 -D
lsattr -E -l sys0 -D
How to remove & delete the device(tape) information from database.
Ans : rmdev -l rmt0 -d
How to make defined device(tape) to available .
Ans : mkdev -l rmt0
How to see the real memory of the system ?
Ans : lsdev -Cc memory or
lsattr -E -l mem0
how to check lun information of SAN environment in AIX
Ans : using lsdev
How to see the firmware
Ans : lsattr –El sys0 –a fwver
Filesystem
Lists out the Advantage of Having LVM .
Optimizing the LV for maximum performance
Increasing the filesystem size dynamically
Mirroring of LVs
Striping of logical volumes
What is the limitation of LVM ?
Maximum VGs per system is 255
Maximum PVs per VG is 32
Maximum LVs per VG is 256
Maximum PPs per PV is 1016 ( AIX 4.3 supports multiple numbers )
Striped logical volume can not be mirrored
Moving data acrross VG is not possible
Reducing the size of LV is not possible.
What is superblock
The first block on any file system that contain metadata of its like no:of inode and free inode etc.
How to restricts the VG spaning on numbers of PVs? Is there any smit is available?
With mkvg command you have to use -d flag to limit the VG spanning across more disks
There is not smit available.
How to restricts I/O operation on particular PV?
# chpv -v r pvname
What is the Command used to migrate the PV & LV? Is it possible to migrate the PV between VGs if not possible, how to copy the LVs from one VG PV to other VG PVs.
#migratepv
It’s not possible
migratelv -v VGName -y LVName
How will you create filesystem?
A. crfs -v fstype -g volgroup -m mountpt -p permission -a size
How will you convert normal vg to big vg.
A. chvg -B vgname
Q9.What is the use of synvg and synclvodm
A. syncvg:to update mirrored lv copy in a vg
synclvodm:Synchronizes or rebuilds the logical volume control block,
the device configuration database, and the volume group descriptor areas
on the physical volumes.
Q9.How many lvs will be created at the time of AIX installation?
A. This is indexnode containing the information about the file like filename, filesize, fileowner, filegroup, access date& time, Modification date & time etc.
Q13-How many pvs possible in Big VG & Scalable VG?
A. This is 128 & 1024
Q14-How will you define the VG?
A # mkvg -s pp_size -t t-factor -y vg_name hsidkx
Q15.How will you change the normal VG to Big VG?
A. #chvg -B vg_name
Q16-What is t-factor?
It is the factor used for define the no.of PP's in a PV within the VG,if we are putting the value of t-factor 2 it will extend the max no:of PP's per PV and reduced the max no:of PV's within the VG
Q17- How many max LV possible in a scalable VG?
These are 4096 per VG
Q18.What is the use of lvlstmajor command?
Ans- To knows the free Major Number.
Q19.How to increase the filesystem size, can we reduce the fs size?
Ans- #chfs -a size=+value /fsname, fs size can be reduce in Aix5.3 not in Aix 5.1
Q20.How will you move pp to particular disk?
Migratelp
To move the first logical partitions of logical volumelv00 to hdisk
Migratelp lv00/1 hdisk1
Q21.How to create LV?
Ans. #mklv -t -y
t- for type it may be jfs,pagingspace,journallog,boot type.
Q22. How to replace the mirror disk from rootvg?
Ans-#unmirrorvg rootvg pvname
#sysdumpdev -p /dev/sysdumpnull
#reducevg rootvg pvname
#rmdev -dl hdiskx
if mirror disk is bootable put #chpv -c hdiskx
Now remove faulty disk and put new one then run #cfgmgr
#extendvg rootvg hdisky
#mirrorvg -S rootvg hdisky
#bosboot -ad /dev/hdisky
#bootlist -m normal hdisky
Q23. What is Quorum?
This is the voting of VGDA,used to recover the data after a disk crash,if VGDA area is >51% ,then only the quorum will come in picture. Quorm is provide datat intigrity, data redundancy in mirrorvg.
Q24.How would you increase(Manage) the Filesystem size?
Ans. This depends upon the name of the filesystem. If its /usr then normally we have to increase the filesystem, because we don't have chances of compressing the files. In case of other filesystems like /var, we compress the old log files. Some times we inspect the data which is not required, we delete that after taking the backups and consulting the appropriate persons. In case we have to increase the Filesystem size then we follow the procedure as: To check the no. of free PPs in filesystems using "lsvg -p" command and the size of the PP in VG. Then we increase the FS size by:
chfs -a size=+NewSize(M\G\or 512 Bytes multiple) Name_of_FS
If the no. of free PPs is insufficient then we have to add new harddisk, extend
the VG and then run the chfs command again.
Q25 What is the command for synchronizing a logical volume copy (mirror)?
Ans. # syncvg name could be VG, PV or LV name.
Q26 Write down the command for turning off a mirroring of a logical volume ?
Q28. How do I get rid of a disk that is no longer really in the volume group?
Ans. # reducevg -d -f
# reducevg -d -f
Q.29 Can you define different Quotas on different filesystems for a single user?
Ans. Yes.
Q.30 What is LVCB ?
Ans. The logical volume control block (lvcb) is the first 512 bytes of a logical volume. This area holds important information such as the creation date of the logical volume,
information about mirrored copies, and possible mount points in a journaled filesystem.
Q.31. File systems - nbpi, etc., read the theory.
Ans. nbpi – number of bytes per inode.
This feature of filesystem is used when fragmentation of files are set. If a filesystem contains small files , then it is advantageous to keep the fragment size small , so that space is not wasted. Normally there is one inode created for every possible file in a filesystem. However in actual practice the number of inodes required are quite less. Therefore to save on space allocated for inodes , we specify the nbpi value.
Q.32. Why am I having trouble adding another disk to my VG?
Ans. a.) Not enough space left in the volume group descriptor area.(VGDA)
b.) Volume group can have a maximum of 32 disks in a volume group. ( 128 for big VG)
Q33.Difference between fsck –y and fsck –f
Ans : fsck –f: perform the fast check. It will not check that filesystem were umounted successfully.
FSCK –y : assumes a yes response to all questions asked by the fsck command
What are the 6 steps in fsck –y
Check Block and size
Check pathname
Check connectivity
Check reference counts
Check inode map
Check block map
Q34.How to create file system in raw hard disk?
Extendvg, mklv, crfs
Q35.What are the stanza in /etc/filesystem?
Dev= ,Mount= ,Log= ,Vfs= , Check= ,Type=
Q36.What is proc file system?
Contain info about all currently running process
calculation of pp
pv size = 80GB (81920 MB)
default no of pp = 1016
pp size = h/d in mb / default no of pp (81920/1016) = 80mb (>64) that’s why 128 mb
if we want to increase no of pp = t factor increase
no of pp = default no of pp * t factor ( 1016*2 = 2032 pp)
according that if we want to decrease size of PP then we have to increase t factor mean no of pp
ppsize now = 81920/2032 = 40mb means >32 that’s why it’s a 64 mb
Q37.How you will maintain the password polices?
Using chuser and /etc/security/user
Q38.What is journaled file system?
It maintains a log in corresponding log device before committing any changes to LV and thus maintains integrity of file system.
Boot & dump * Error & ODM
Q.1. How to see memory activity ?
Ans. Using "sar", "vmstat"
Q2.What is difference between tar and cpio?
Ans : Tar handle symbolic link. cpio doesn’t.
Q3.What will do when odm in non-rootvg corrupted? (Rename vg also)
Ans :Exportvg and importvg
Q4.Why quorum is disabled in mirroring.
Ans : If it is mirrored within two pv VGDA will be three, one will have two VGDA means 66%, another ill have one VGDA means 33% , we can`t activate which failed with in 51% VGDA.. that’s what quorum is disabled in two mirrored condition.
Q5.Will file system extend or reduce update the vgda?
Ans : Yes as the use of pp is maintained by the vgda
Q.6. How to install software ?
Ans. # installp –a –Q –d -f ‘all latest’
-a Applies one or more software products or updates.
-d Device Specifies where the installation media can be found.
-f ListFile Reads the names of the software products from ListFile.
Q.7 What are the packages to be installed for man pages & networking?
Ans. bos.info and bos.net
Q.8 How do you remove an installed package?
Ans. # installp –u –f listfile
Q.9 What is the use of mkszfile?
Ans. Saves the system state for reinstallation on the current system or another system. The mkszfile command overwrites an existing /image.data file with new information.
Q.10 Write down the command for checking bootlog?
Ans. # alog -o -t boot
Q.11. How to take the backup of a dump?
Ans. # snap -a -o
Q.12 What is echo $$ ?
Ans. Returns current shell’s PID
Q.13. How to debug shell script ?
Ans. $ sh -x shellfile.
Q.14 What are the packages to be installed for man pages & networking?
Ans. bos.info and bos.net
Q.15 How do you remove an installed package?
Ans. # installp –u –f listfile
Q16.How will you delete an entry from ODM?
Ans : #odmdelete
Q17.What is the component of BLV?
Ans- These are Reduce ODM, RAMfs, Aix Kernel, Aix Commands
Q18.How to Recover BLV if corrupted, which LED will Glow for that?
Ans-Boot the system by Cd or tape in Maintenance mode and access the rootvg then run #bosboot -ad /dev/hdiskx command set set the bootlist and restart the system. LED 557 will glow.
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