The bug was first described in ZfsOnLinux, see here: https://github.com/zfsonlinux/zfs/commit/335b251ac1a1f8ba8434450dc0f24986bc44f688 The way to reproduce it is found here: https://github.com/zfsonlinux/zfs/issues/5806 I can reproduce it on FreeBSD 11.0-RELEASE. It was resolved by code in the first link. As far as I can tell it has not landed in CURRENT, yet. Could somebody look into this? Thank you, George
This only landed upstream 3 days ago, but it is a small fix so we should be able to grab it easily.
This should get merged in time for 11.1 since it is low risk and high impact.
Is it possible to MFC this one (MFV r318942) to 11.1-RELEASE? Thank you, George
A commit references this bug: Author: gjb Date: Tue Jun 6 14:46:23 UTC 2017 New revision: 319624 URL: https://svnweb.freebsd.org/changeset/base/319624 Log: MFC r318943 (avg): MFV r318942: 8166 zpool scrub thinks it repaired offline device https://www.illumos.org/issues/8166 If we do a scrub while a leaf device is offline (via "zpool offline"), we will inadvertently clear the DTL (dirty time log) of the offline device, even though it is still damaged. When the device comes back online, we will incompletely resilver it, thinking that the scrub repaired blocks written before the scrub was started. The incomplete resilver can lead to data loss if there is a subsequent failure of a different leaf device. The fix is to never clear the DTL of offline devices. Note that if a device is onlined while a scrub is in progress, the scrub will be restarted. The problem can be worked around by running "zpool scrub" after "zpool online". See also https://github.com/zfsonlinux/zfs/issues/5806 PR: 219537 Approved by: re (kib) Sponsored by: The FreeBSD Foundation Changes: _U stable/11/ stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
A commit references this bug: Author: gjb Date: Tue Jun 6 14:46:46 UTC 2017 New revision: 319625 URL: https://svnweb.freebsd.org/changeset/base/319625 Log: MFC r318943 (avg): MFV r318942: 8166 zpool scrub thinks it repaired offline device https://www.illumos.org/issues/8166 If we do a scrub while a leaf device is offline (via "zpool offline"), we will inadvertently clear the DTL (dirty time log) of the offline device, even though it is still damaged. When the device comes back online, we will incompletely resilver it, thinking that the scrub repaired blocks written before the scrub was started. The incomplete resilver can lead to data loss if there is a subsequent failure of a different leaf device. The fix is to never clear the DTL of offline devices. Note that if a device is onlined while a scrub is in progress, the scrub will be restarted. The problem can be worked around by running "zpool scrub" after "zpool online". See also https://github.com/zfsonlinux/zfs/issues/5806 PR: 219537 Sponsored by: The FreeBSD Foundation Changes: _U stable/10/ stable/10/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c