Summary: ALthough AIX is by now on version 7.3 I find these old pages so fascinating I decided to keep them. On this page I'll show you how to migrate data from one physical volume to another on AIX using the migratepv command.. This page is for AIX 5.3 and AIX 6.1.
Date: Between 2010-2013
Refactor: 21 December 2024: Checked formatting.

This is an article about migrating data from one physical volume to another on AIX using the migratepv command.
This is the scenario:

• An AIX VIOS server with multiple LPARs on it
• All data is now on a old SAN
• There is a new SAN and we want to migrate all data to the new SAN without downtime

To do so, we'll start with migrating the LPARs and then the VIOS server. They can all be done using the migratepv command.

We start with LPAR2, which is an AIX 6.1 TL 6 FP 2 testmachine. It has one volume group consisting of 1 hdisk:

sjoerd@lpar2:/home/sjoerd>lsvg
rootvg
sjoerd@lpar2:/home/sjoerd>lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            957         415         159..03..00..61..192

After creating the LUN on the new SAN and assigning it to the LPAR you can discover it:

root@lpar2:/home/root>cfgmgr
root@lpar2:/home/root>lspv
hdisk0          000a447a24a494e9                    rootvg          active
hdisk1          none                                None

Note two things: I switched to root and there is a new available physical volume available.

Don't forget to add the new disk to the rootvg volume group, migratepv can only move data between physical volumes in the same volume group:

root@lpar2:/home/root>extendvg rootvg hdisk1
0516-1254 extendvg: Changing the PVID in the ODM.
root@lpar2:/home/root>lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            957         415         159..03..00..61..192
hdisk1            active            959         959         192..192..191..192..192

Because the rootvg is the only volume group it is also the volume group that contains the boot image. In this case it's necessary to first move the logical volume that contains the boot image to the new disk.

First find the logical volume that holds the boot image:

root@lpar2:/home/root>lsvg -l rootvg
rootvg:
LV NAME             TYPE       LPs     PPs     PVs  LV STATE      MOUNT POINT
hd5                 boot       1       1       1    closed/syncd  N/A
...<cut>...

Then migrate the data for the logical volume hd5:

root@lpar2:/home/root>migratepv -l hd5 hdisk0 hdisk1
0516-1246 migratepv: If hd5 is the boot logical volume, please run 'chpv -c hdisk0'
        as root user to clear the boot record and avoid a potential boot
        off an old boot image that may reside on the disk from which this
        logical volume is moved/removed.
root@lpar2:/home/root>
root@lpar2:/home/root>lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            957         416         160..03..00..61..192
hdisk1            active            959         958         191..192..191..192..192

As you can see, there is one PP less in use on the old disk and one PP is in use on the new one. Now we have to run the command displayed in the message warning, to clear the old disk from the boot record:

root@lpar2:/home/root>chpv -c hdisk0

Now we define the new disk as the boot disk by rebuilding the boot image:

root@lpar2:/home/root>bosboot -a -d hdisk1

bosboot: Boot image is 45155 512 byte blocks.

And to make sure the server boots without interruption or intervention we'll also update the bootlist:

root@lpar2:/home/root>bootlist -m normal hdisk1

Now we're done with the boot image, we'll start the rest:

root@lpar2:/home/root>migratepv hdisk0 hdisk1

Check whether all data has been removed from hdisk0:

root@lpar2:/home/root>lsvg -p rootvg
rootvg:
PV_NAME           PV STATE          TOTAL PPs   FREE PPs    FREE DISTRIBUTION
hdisk0            active            957         957         192..191..191..191..192
hdisk1            active            959         385         127..08..00..58..192

After migrating the data we can remove the old disk from the SAN:

root@lpar2:/home/root>reducevg rootvg hdisk0
0516-1734 reducevg: Warning, savebase failed.  Please manually run 'savebase' before rebooting.
root@lpar2:/home/root>savebase

Now you can remove the old disk and disconnect it from the SAN:

root@lpar2:/home/root>rmdev -dl hdisk0
hdisk0 deleted

LPAR 1 was a AIX 5.3 TL 12 FP 2 box and everything worked exactly the same.

You can do the VIOS (Virtual IO Server) exactly the same way, except that you first have to issue the command “oem_setup_env” so you can use the normal AIX commands.