Sharing physical volumes across logical partitions on IBM Power Systems servers
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Sharing the same PVs across multiple LPARs
This article provides the process for sharing the same PVs across multiple LPARs.
These PVs can be:
1. Available on the IBM® Power Systems™ servers, which are assigned to Virtual I/O Server (VIOS).
2. From the storage area network (SAN) and assigned to VIOS.
In this example, we are sharing four PVs hdisk5, hdisk6, hdisk7, hdisk8 among three LPARs sys1, sys2, sys3.
Log in to the VIOS using padmin ID and password.
Login ID: padmin
Login password: padmin's password
Last unsuccessful login: Thu Apr 1 00:12:40 CDT 2010 on /dev/vty0
Last login: Sat Jul 21 00:03:49 CDT 2012 on /dev/vty0
To perform the administrative tasks, run the oem_setup_env command.
Checking the physical volume IDs and generating new ones
Check the physical volume identifier (PVID) of the disks by using the lspv command.
If you notice that a disk does not have the PVID or there are duplicate PVIDs, then clear the PVIDs and set the PVID again.
Clearing the PVIDs:
#chdev -l hdisk5 -a pv=clear #chdev -l hdisk6 -a pv=clear #chdev -l hdisk7 -a pv=clear #chdev -l hdisk8 -a pv=clear
Getting the PVIDs again for the PVs:
#chdev -l hdisk5 -a pv=yes #chdev -l hdisk6 -a pv=yes #chdev -l hdisk7 -a pv=yes #chdev -l hdisk8 -a pv=yes
Changing the reserve policy
As we need to assign the same disk to multiple LPARs, change the reserve policy to
no. Otherwise, we cannot assign them.
Changing the reserve policy:
#chdev -l hdisk5 -a reserve_policy=no_reserve #chdev -l hdisk6 -a reserve_policy=no_reserve #chdev -l hdisk7 -a reserve_policy=no_reserve #chdev -l hdisk8 -a reserve_policy=no_reserve
Now exit from oem_setup_env.
Assigning the disks to LPARs
Map (assign) the disks to each LPAR.
The vhost4 adapter is assigned to the sys1 LPAR and all the disks are assigned to the same virtual Small Computer System Interface (VSCSI) adapter, vhost4.
mkvdev -f -vdev hdisk5 -vadapter vhost4 -dev sys1_hdisk5 mkvdev -f -vdev hdisk6 -vadapter vhost4 -dev sys1_hdisk6 mkvdev -f -vdev hdisk7 -vadapter vhost4 -dev sys1_hdisk7 mkvdev -f -vdev hdisk8 -vadapter vhost4 -dev sys1_hdisk8
The vhost5 adapter is assigned to the sys2 LPAR and all the disks are assigned to the same virtual SCSI adapter, vhost5.
mkvdev -f -vdev hdisk5 -vadapter vhost5 -dev sys2_hdisk5 mkvdev -f -vdev hdisk6 -vadapter vhost5 -dev sys2_hdisk6 mkvdev -f -vdev hdisk7 -vadapter vhost5 -dev sys2_hdisk7 mkvdev -f -vdev hdisk8 -vadapter vhost5 -dev sys2_hdisk8
The vhost6 adapter is assigned to the sys3 LPAR and all the disks are assigned to the same virtual SCSI adapter, vhost6.
mkvdev -f -vdev hdisk5 -vadapter vhost6 -dev sys3_hdisk5 mkvdev -f -vdev hdisk6 -vadapter vhost6 -dev sys3_hdisk6 mkvdev -f -vdev hdisk7 -vadapter vhost6 -dev sys3_hdisk7 mkvdev -f -vdev hdisk8 -vadapter vhost6 -dev sys3_hdisk8
Now, log in to the respective LPARs and run the
Check the PVIDs of the disks using the
The PVID should be same among all the LPARs.
General usage of this setup
This kind of setup is mainly used in cluster environments.
As I belong to an IT team, I have configured this for the following scenarios:
1. For a cluster environment of IBM AIX® servers
2. When there is a need to share the same storage for IBM DB2® cluster services
3. For cluster or IBM PowerHA® environments, when we use the same PVs for failover in an active-standby scenario
Here are a few useful examples that are relative to this document:
- Find everything about IBM developerWorks® at the developerWorks main page.
- Learn about assigning PVID to hdisks.
- Learn about dealing with duplicate PVIDs for rootvg