VIOS FAQ
VIOS frequently asked
questions
The Virtual I/O Server is an appliance that
provides virtual storage and shared Ethernet adapter capability to client
logical partitions on POWER5 systems. It allows a physical adapter with
attached disks on the Virtual I/O Server partition to be shared by one or more
partitions, enabling clients to consolidate and potentially minimize the number
of physical adapters required.
Yes. The below VIOs website contains
links to documentation, hints and tips, VIOS updates and fixes.
The VIOS documentation can be found online
in the below link.
N_Port ID
Virtualization(NPIV) is a standardized method for virtualizing a physical fibre
channel port. An NPIV-capable fibre channel HBA can have multiple N_Ports, each
with a unique identity. NPIV coupled with the Virtual I/O Server (VIOS) adapter
sharing capabilities allow a physical fibre channel HBA to be shared across
multiple guest operating systems. The PowerVM implementation of NPIV enables
POWER logical partitions (LPARs) to have virtual fibre channel HBAs, each with
a dedicated world wide port name. Each virtual fibre channel HBA has a unique
SAN identity similar to that of a dedicated physical HBA.
The minimum
requirement for the 8 Gigabit Dual Port Fibre Channel adapter, feature code
5735, to support NPIV is 110304. You can obtain this image from the http://www-933.ibm.com/support/fixcentral/
Virtual
SCSI is based on a client and server relationship. The Virtual I/O Server owns
the physical resources and acts as server, or target, device. Physical adapters
with attached disks on the Virtual I/O Server partition may be shared by one or
more partitions. These partitions contain a virtual SCSI client adapter that
sees these virtual devices as standard SCSI compliant devices and LUNs.
A shared
Ethernet adapter is a bridge between a physical Ethernet adapter or link
aggregation and one or more virtual Ethernet adapters on the Virtual I/O Server.
A shared Ethernet adapter enables logical partitions on the virtual Ethernet to
share access to the physical Ethernet and communicate with stand-alone servers
and logical partitions on other systems. The shared Ethernet adapter provides
this access by connecting the internal VLANs with the VLANs on the external
switches.
See the http://www14.software.ibm.com/webapp/set2/sas/f/vios/documentation/datasheet.html for supported storage and configurations.
1. AIX
5.3 and AIX 6.1 TL 2
2. SUSE
LINUX Enterprise Server 9 for POWER
3. Red
Hat Enterprise Linux AS for POWER Version 3(update 2 or newer)
4. Red
Hat Enterprise Linux AS for POWER Version 4
5. IBM
i
Virtual
SCSI disk devices are standard SCSI compliant devices that support all
mandatory SCSI commands. Solutions that have special requirements at the device
level should consult the IBM Solutions team to determine if the device meets
your requirements.
The VIOS
datasheet includes some information on VSCSI solutions.
That is,
given a physical SCSI device(ie LUN), with user data on it, that resides in a
SAN environment; can this device be allocated to a VIOS and then provisioned to
a client partition and used by the client as is?
No, this is
not supported at this time. The device cannot be used as is, virtual SCSI
devices are new devices when created, and the data must be put onto them after
creation. This typically would require some type of backup of the data in the
physical SAN environment with a restoration of the data onto the virtual disk.
11) In the
context of virtual I/O, what do the terms server, hosting, client, and hosted
partition mean?
Server and
hosting partition is synonymous, as is client and hosted. The server/hosting
partition(s) own physical resources and facilitates the sharing of the physical
resource amongst the client/hosted partition(s).
The Linux
and IBM i operating systems do provide various virtual I/O server/hosting
features(virtual SCSI, ethernet bridging, etc). AIX does not provide virtual
I/O server/hosting capabilities. There is only one product named the Virtual
I/O Server. It is a single function appliance that provides I/O resource to
client partitions, and does not support general purpose applications.
The VIOS is
not AIX. The VIOS is a critical resource and as such, the product was
originally based on a version of the AIX operating system to create a
foundation based on a very mature and robust operating system. The VIOS
provides a generic command line interface for management. Some of the commands
in the VIOS CLI may have common names with AIX and Linux commands. These
command names were chosen only because they were generic, the flags and
parameters will differ. While some of the VIOS commands may drop the user into
an AIX-like environment, this environment is only supported for the installing
and setup of certain software packages(typically software for managing storage
devices, see the VIOS's Terms and Conditions). Any other tasks performed in
this environment are not supported. While the VIOS will continue to support
it's current user interfaces going foward, the underlying operating system may
change at any time.
The sole
purpose of the oem_setup_env VIOS CLI command is for ease in installing and
setting up certain software packages for the VIOS. See the VIOS datasheet for a
list of supported VIOS software solutions.
Please see
the section titled "Planning for Virtual SCSI Sizing Considerations"
in the VIOS online pubs in InfoCenter.
The VIOS
online pubs in InfoCenter include sections on sizing for both Virtual SCSI and
SEA. For Virtual SCSI, please see the section titled "Planning for shared
Ethernet adapters".
In
addition, the WorkLoad Estimator Tool is being upgraded to accommodate virtual
I/O and the VIOS.
Typical
multipathing solutions provide two key functions: failover and load balancing.
MPIO for VSCSI devices does provide failover protection. The benefit of load
balancing is less obvious in this environment. Typically, load balancing allows
the even distribution of I/O requests across multiple HBA's of finite resource.
Load balancing for VSCSI devices would mean distributing the I/O workload
between multiple VIOS's. Since the resources allocated to a given VIOS can be
increased to handle larger workloads, load balancing seems to have limited
benefit.
The
Advanced POWER Virtualization feature is a package that enables and manages the
virtual I/O environment on POWER5 systems. The main technologies include:
- Virtual I/O Server
- Virtual SCSI Server
- Shared Ethernet Adapter - Micro-Partitioning technology
- Partition Load Manager
The primary benefit of Advanced POWER Virtualization is to
increase overall utilization of system resources by allowing only the required
amount of processor and I/O resource needed by each partition to be used.
19) What are some of the restrictions
and limitations in the VIOS environment?
- Logical volumes used as virtual disks must be less than 1 TB in size.
- Logical volumes on the VIOS used as virtual disks cannot be mirrored, striped, or have bad block relocation enabled.
- Virtual SCSI supports certain Fibre Channel, parallel SCSI, and SCSI RAID devices as backing devices.
- Virtual SCSI does not impose and software limitations on the number of supported adapters. A maximum of 256 virtual slots can be assigned to a single partition. Every virtual slot that is created requires resources in order to be instantiated. Therefore, the resources allocated to the Virtual I/O Server limits the number of virtual adapters that can be configured.
- The SCSI protocol defines mandatory and optional commands. While virtual SCSI supports all of the mandatory commands, some optional commands may not be supported at this time.
- The Virtual I/O Server is a dedicated partition to be used only for VIOS operations. No other applications can be run in the Virtual I/O Server partition.
- Future considerations for VSCSI devices: The VIOS uses several methods to uniquely identify a disk for use in as a virtual SCSI disk, they are:
- Unique device identifier(UDID)
- IEEE volume identifier
- Physical volume identifier(PVID)
Each of these methods may result in different data formats on
the disk. The preferred disk identification method for virtual disks is the use
of UDIDs.
MPIO uses the UDID method.
Most non-MPIO disk storage multi-pathing software products use the PVID method instead of the UDID method. Because of the different data format associated with the PVID method, customers with non-MPIO environments should be aware that certain future actions performed in the VIOS LPAR may require data migration, that is, some type of backup and restore of the attached disks. These actions may include, but are not limited to the following:
MPIO uses the UDID method.
Most non-MPIO disk storage multi-pathing software products use the PVID method instead of the UDID method. Because of the different data format associated with the PVID method, customers with non-MPIO environments should be aware that certain future actions performed in the VIOS LPAR may require data migration, that is, some type of backup and restore of the attached disks. These actions may include, but are not limited to the following:
- Conversion from a Non-MPIO environment to MPIO
- Conversion from the PVID to the UDID method of disk identification
- Removal and rediscovery of the Disk Storage ODM entries
- Updating non-MPIO multi-pathing software under certain circumstances
- Possible future enchancements to VIO
- Due in part to the differences in disk format as descibed above, VIO is currently supported for new disk installations only
- Considered when implementing shared Ethernet adapters:
- Only Ethernet adapters can be shared. Other types of network adapters cannot be shared.
- IP forwarding is not supported on the Virtual I/O Server.
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