>>> On Thu, 18 May 2023 15:13:24 +0100, Peter Grandi via lustre-discuss >>> <[email protected]> said:
>> You might want to take a look at this: >> https://www.opensfs.org/wp-content/uploads/2017/06/Wed06-CroweTom-lug17-ost_data_migration_using_ZFS.pdf > I was indeed reading that but I was a bit hesitant because the > "zpool"/"zfs" operations are bracketed by 'service lustre stop > ...'/'service lustre start ...' commands which I hope to avoid. So doing a snapshot of the MDT "filesystem" and then doing 'zfs send' of it just works well. I think that: * It may be important that the shapshot be read-only * The snapshotting should be preceded by 'barrier_freeze' and followed by 'barrier_thaw'. * It is also useful to have the option '-s' on 'zfs receive' to make the 'zfs send' restartable. * Probably the snapshot can be done *without* a 'barrier_freeze' first, then once it is done one can do 'barrier_freeze', then take another snapshot, then 'barrier_thaw' and then send that very short incremental, to minimize the time where the Lustre instance is frozen. I will find the time to request an update of the backup sexction of the Lustre operations manual to document this. With the ZFS backend improvements in recent years I guess that ZFS rather than 'ldiskfs' should currently be the default storage backend for MDTs too. _______________________________________________ lustre-discuss mailing list [email protected] http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
