Peter, 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
It's a few years old, but it shows how IU used zfs send/receive to copy data from osts. I worked with someone several years ago to do basically the same procedure to make incremental copies of mdt data when we were attempting to switch over to a new mds server. You don't need to unmount lustre in order to do the incremental backups. --Rick On 5/18/23, 9:38 AM, "lustre-discuss on behalf of Peter Grandi via lustre-discuss" <lustre-discuss-boun...@lists.lustre.org <mailto:lustre-discuss-boun...@lists.lustre.org> on behalf of lustre-discuss@lists.lustre.org <mailto:lustre-discuss@lists.lustre.org>> wrote: I have a Lustre 2.15.2 instance "temp01" on ZFS 2.1.5 (on EL8), and I just want to backup the MDT of the instance (I am mirroring the data on two separate "pools" of servers). The "zpool" is called "temp01_mdt_000" and so is the filesystem, so the '/etc/fstab' mount line is (I have set legacy ZFS mount-points): > temp01_mdt_000/temp01_mdt_000 /srv/temp01/temp01_mdt_000 lustre > defaults,noatime,auto 0 0 As usual '/srv/temp01/temp01_mdt_000' is opaque (no access permissions) when mounted as 'lustre', but anyhow I would like to backup a snapshot of it, using 'zfs send'. If I use 'zpool list' and 'zfs list' I see the relevant details even if it is mounted as 'lustre'. If I un-mount it and re-mount it as 'zfs' it looks ordinary, but I would rather not do that. In theory, however it is mounted, I should be able to (suitably preceded by 'lctl barrier_freeze') create a snapshot for it, and mount that as 'zfs' to some other mount-point and then 'zfs send' that. Before doing it on a live Lustre instance (I can't easily afford to setup a test Lustre instance in the short run) I would like some confirmation that this is meant to work ideally by someone who does it routinely :-). _______________________________________________ lustre-discuss mailing list lustre-discuss@lists.lustre.org <mailto:lustre-discuss@lists.lustre.org> https://urldefense.us/v2/url?u=http-3A__lists.lustre.org_listinfo.cgi_lustre-2Ddiscuss-2Dlustre.org&d=DwICAg&c=v4IIwRuZAmwupIjowmMWUmLasxPEgYsgNI-O7C4ViYc&r=SpEwA4Pnyq7nH7aMGq8KpA&m=IL-tAnpVG0zDmIcadFEhpvjcYSfKQOVy2N17rJokQM3BHR_ICfc_JTGFR6euTBAL&s=dqTFpK0IyU_gT7eF3npzRFYtt7N7AXnGk3tQCHcjiUs&e= <https://urldefense.us/v2/url?u=http-3A__lists.lustre.org_listinfo.cgi_lustre-2Ddiscuss-2Dlustre.org&d=DwICAg&c=v4IIwRuZAmwupIjowmMWUmLasxPEgYsgNI-O7C4ViYc&r=SpEwA4Pnyq7nH7aMGq8KpA&m=IL-tAnpVG0zDmIcadFEhpvjcYSfKQOVy2N17rJokQM3BHR_ICfc_JTGFR6euTBAL&s=dqTFpK0IyU_gT7eF3npzRFYtt7N7AXnGk3tQCHcjiUs&e=> _______________________________________________ lustre-discuss mailing list lustre-discuss@lists.lustre.org http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org