Move guests from XP to EVA

[G Klettke]

I need to move the storage of our virtual machine hosts v4.1 from XP to EVA. All guest
backing stores are based on whole disk and are presented via agile device file. Is it possible to halt each guest, replicate the XP LUN (using dd or some such raw copy command) to the EVA LUN, unpresent the XP backing store and present the new the EVA backing store to the guest using the same Bus, target etc. Would this form of data movement work?

I think it might be easier to do data replication at the host level rather than
at the guest level. The guests (HP-UX v2 and v3) are using LVM so the other method would be to present EVA LUNs to each and replicate data using LVM mirroring. This might be less disruptived and/or quicker , but does involve a lot of grinding about with LVM. Comments?

[Prasanth V Aravind]

1:- using dd or some such raw copy command

i feel dd command is very useful if you have to migrate raw data or row lv. Most of the time you have to do fsck before mounting after dd completes. so in this case i am not sure how dd going to work? rather than you have to shutdown your entire applications to avoid any kind of r/w on source volume. which make longer downtime in case of more data.

2:-replicate data using LVM mirroring.

this one is a nice option, if you doesn't want any downtime. you can perform migration online. But very important.... if your application is i/o intensive & mirroring will increase the load on your disks. this will impact application performance. So recommend to do on offload time.

GUdluck
Prasanth.

[melvyn burnard]

How many LUN's per Virtual Machine do you have?
To sort out the boot disk, simply present the new LUN to the Virtual Machine, use DRD (on the guest) to clone the exisiting boot disk, activate the clone and reboot to the new boot disk, remove the OLD boot disk from the Virtual Machine

[Eric SAUBIGNAC]

Bonjour,


As mentionned by Melvyn, have special care with boot volume disk. Unless an XP volume of N GB gives exactly the same size than an EVA volume of N GB, don't try to copy it with dd. You could have some bad surprises. For exemple see this this thread where reducing the size of a boot disk was a disaster though it was done in a reasonable way (in my mind ;-) : http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1392503

So use DRD, or ignite why not, to move vg00 to the EVA. One more thing : if 'dd' could work with the boot disk, you will probably still have to create back the boot entry in the EFI menu.

With others disks, 'dd' should work : assuming the target disk has exactly the same size or more than the original one.

As well as LVM Mirror.

Not sure what you mean with "a lot of grinding" at LVM level, but in my mind 'dd' will not be necessary an easier way to do the migration. Just a different way than with LVM Mirror. It depends on your skill with LVM ;-) but it is not so complex.

Some adavantages of LVM Mirror :

- just copy allocated data. If your VG has some free PE, it will be faster than a dd on a whole disk.

- if you have several LVs in the VGs, you will be able to do it in more granular way. So maybe minimize impacts on others VM.

- with 'dd' you can distroy an original disk if you are in the moon. LVM stack delivers some basic controls.

Eric

[G Klettke]

Melvin asked how many LUNs are in use by the guests. The answer is there are 36 guests using approx 74 data LUNs. Each guest has 1 to 3 data LUNs. Each data LUN is approx 36 GB.

DRD sounds like a good option for the O/S disk. I'm not a bit dd fan but will use it when advantageous. A good point is that dd will copy the entire disk used or not so that may burn considerably more time that necessary.

[G Klettke]

No more hits...no more case.

Shalom