Migrate shark to DMX-4 on AIX 5.2

[rondebbs]

I have many AIX Volme Groups on the shark similar to this -

appvg:
vpath0 active 147 0
vpath1 active 147 0
vpath2 active 147 0

The AIX box does not use EMC PowerPath yet. I wanted to install PP and use AIX mirrorvg to migrate -

extendvg appvg hdiskpower0 hdiskpower1 hdiskpower2
mirrorvg appvg hdiskpower0 hdiskpower1 hdiskpower2
unmirrorvg appvg vpath0 vpath1 vpath2
reducevg appvg vpath0 vpath1 vpath2

I have migrated AIX with PP from cx to dmx like this several times and can do this on the fly without interrupting users as the mirrorvg runs in background at a fairly low priority. I have never done this with a non PP shark box. The team members are concerened that if we install PP5 and reboot - that PP would interfere with the shark vpath devices. PP may make them hdiskpower devices. I believe the AIX box is using mpio to manage multi path IO on the shark.

Should I be concened with running PP with the shark?

The team would like to connnect one adapter to the new DMX without PP. The new symm devices will be discovered (after cfgmgr) as something like hdisk101, hdisk102 .. rather than hdiskpower1. Then mirrovg the vpath disks to the hdisk101, 102 etc. When everyone is comfortable that we are running fine on the dmx we would finally export the VGs and install PP then reboot. We would then importvg -y appvg hdiskpower101? Hmmmm, I'm not sure if this makes sense or not. What do you think?

My hopes would be that the shark with mpio and the dmx with PP can co-exist in order to do the migration with no need to exportvg/importvg.

 

[MoreFeo]

At a previous client, they were migrating from Hitachi to DMX, and what they did was to leave the Hitachi with only one path and connect to the DMX thru only one path.
Then extendvg and migratepv (no mirrorvg) without PowerPath on hdiskXXX.
Then remove hdisks from hitachi, remove connection with hitachi, connect to second path to DMX and install powerpath.

Once installed PP and rebooted it started using hdiskpowerXX instead of hdiskXXX, with no exportvg/importvg.

This method was given by EMC guys.

 

[rondebbs]

This is very interesting. I wasn't sure that the VG would automatically swap out the hdiskxx to hdiskpowerxx. If you had -

appvg:
hdisk101
hdisk102

you then install PP and reboot and you end up with -

appvg:
hdiskpower0
hdiskpower1

Is this really how it works. If this is the case that would be great. It sounds like I could use mirrorvg or migratepv. The team prefers mirrorvg becaue for a period of testing the VG would be on the shark and the dmx. We would then unmirrovg/reducevg the shark disks.

I have several VGs on each 5.2 ml9 server.

 

[MoreFeo]

Well, I'm not sure if there is any other step to be performed, but I think it works as I said, but perhaps someone could confirm this.

I'm not sure if I'd do a mirror beetwen shark and dmx, I suppose I'd prefer having all the disks of a mirror the same.