disk migration in LINUX

[skt_skt]

Red Hat Enterprise Linux AS release 3 (Taroon Update 9)

lvm-1

I wantted to move the data from one array to another for a production box and looking for online process/tool through which we can avid an outage to application. (Current idea is copy the data offline)

[Ivan Ferreira]

As lvm-1 does not provides mirroring, you don't have too many options.

Depending of the kind and size of data, there may be some tools that may help you to minimize the down time, like rsync, snapshots or RMAN/Dataguard for oracle databases.

[skt_skt]

Have any one tried pvmove on LINUX?

[Matti_Kurkela]

Yes, we migrated a few old RHEL 3 systems back when our old EMC Symmetrixes were replaced with newer ones. We used pvmove, and it worked OK. When working with external storage, I still much prefer RHEL 4 and newer.

Pvmove is a valid strategy, but remember to MAKE SURE YOUR BACKUPS ARE GOOD before starting a pvmove-style migration. If something unexpected happens while pvmove is running (like power going out, or someone tripping over the storage cables) it is possible that your VG will fail to come back up... in which case re-creating the VG from scratch and restoring the data from backups will very probably be the quickest way to get the system back to normal.

Of course, having a pvmove running will eat a big slice of your disk I/O capacity, so you will want to do that at a time when your system is otherwise as idle as possible.

MK

[IT Csar]

1) pvmove is design to modify physical volumes collection under the existing logical volume. If you google this command, you will find enough evidence that even without power outage and system failure, the procedure is NOT production ready.

2) try to deploy combination of snapshot and manual data synchronization to achive mirror storage by hand combat. Depending on amount of data and its modification rate - you can come to full mirror in almost real-time.

3) what is impact of losing some transactions during fall over period. May be you don't have to be perfectionist, just good enough will work.

Good luck