[lustre-discuss] Making a copy of an OST

Andreas Dilger adilger at whamcloud.com
Tue Dec 4 01:22:46 PST 2018

On Nov 21, 2018, at 22:32, Roger Sersted <rs1 at aps.anl.gov> wrote:
> Lustre Server OS Version: CentOS 7.4
> Lustre Server version: 2.10.2
> Server Kernel version: 3.10.0-693.5.2
> Filesystem: ldiskfs
> I have an older disk array with a hardware failure.  I suspect the 
> drives and data are still valid.
> What I plan to do is migrate the data off of a similar model array, move 
> the drives and migrate the data from the failed array.  In order to do 
> this, I need to migrate just an OST to a different device.  I can't use 
> lfs_migrate, because that works at the file level.  I suspect the best 
> route to go is to create a new device and use "dd" to copy the contents 
> of the source device to the target device.
> Is there a better solution?
> Anything I should be aware of regarding dd and an OST?
> The arrays in question are enterprise class systems with caching 
> controllers configured for RAID6.

Hi Roger,
I just noticed your email didn't get a response.

The OST backup/restore process is discussed in the Lustre manual, https://build.whamcloud.com/job/lustre-manual/lastSuccessfulBuild/artifact/lustre_manual.html#dbdoclet.backup_device

Using "dd" is fine, as long as the target device is as the source.

Cheers, Andreas
Andreas Dilger
Principal Lustre Architect

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