Hi, Part of our ceph cluster is using ext4 and we recently hit major kernel instability in the form of kernel lockups every few hours, issues opened: http://tracker.ceph.com/issues/13662 https://bugzilla.kernel.org/show_bug.cgi?id=107301 On kernel.org kernel developpers are asking about ceph usage of xattr, in particular wether there are lots of common xattr key/value or wether they are all differents. I attached a file with various xattr -l outputs: https://bugzilla.kernel.org/show_bug.cgi?id=107301#c8 https://bugzilla.kernel.org/attachment.cgi?id=192491 Looks like the "big" xattr "user.ceph._" is always different, same for the intermediate size "user.ceph.hinfo_key". "user.cephos.spill_out" and "user.ceph.snapset" seem to have small values, and within a small value set. Our cluster is used exclusively for virtual machines block devices with rbd, on replicated (3) and erasure coded pools (4+1 and 8+2). Could someone knowledgeable add some information on ceph use of xattr in the kernel.org bugzilla above? Also I think it is necessary to warn ceph users to avoid ext4 at all costs until this kernel/ceph issue is sorted out: we went from relatively stable production for more than a year to crashes everywhere all the time since two weeks ago, probably after hitting some magic limit. We migrated our machines to ubuntu trusty, our SSD based filesystem to XFS but our HDD are still mostly on ext4 (60 TB of data to move so not that easy...). Thanks in advance for your help, Sincerely, Laurent GUERBY http://tetaneutral.net -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
