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zed: Take no action on scrub/resilver checksum errors
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When scrubbing/resilvering a pool it can be counter productive to
cancel the scan and kick of a replace operation to a hot spare
when encountering checksum errors.  In this case, the best course
of action is to allow the scrub/resilver to complete as quickly
as possible and to keep the vdevs fully online if possible.

Realistically, this is less of an issue for a RAIDZ since a
traditional resilver must be used and checksums will be verified.
However, this is not the case for a mirror or dRAID pool which is
sequentially resilvered and checksum verification is deferred
until after the replace operation completes.

Regardless, we apply this policy to all pool types since it's
a good idea for all vdevs.  Degrading additional vdevs has the
potential to make a bad situation worse.  Note the checksum
errors will still be reported as both an event and by
`zpool status`.  This change only prevents the ZED from
proactively taking any action.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #13499
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behlendorf committed May 27, 2022
1 parent 4184b78 commit 5d534f1
Showing 1 changed file with 20 additions and 0 deletions.
20 changes: 20 additions & 0 deletions cmd/zed/agents/zfs_diagnosis.c
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#include <sys/fs/zfs.h>
#include <sys/fm/protocol.h>
#include <sys/fm/fs/zfs.h>
#include <sys/zio.h>

#include "zfs_agents.h"
#include "fmd_api.h"
Expand Down Expand Up @@ -773,6 +774,8 @@ zfs_fm_recv(fmd_hdl_t *hdl, fmd_event_t *ep, nvlist_t *nvl, const char *class)
ZFS_MAKE_EREPORT(FM_EREPORT_ZFS_PROBE_FAILURE))) {
char *failmode = NULL;
boolean_t checkremove = B_FALSE;
uint32_t pri = 0;
int32_t flags = 0;

/*
* If this is a checksum or I/O error, then toss it into the
Expand All @@ -795,6 +798,23 @@ zfs_fm_recv(fmd_hdl_t *hdl, fmd_event_t *ep, nvlist_t *nvl, const char *class)
checkremove = B_TRUE;
} else if (fmd_nvl_class_match(hdl, nvl,
ZFS_MAKE_EREPORT(FM_EREPORT_ZFS_CHECKSUM))) {
/*
* We ignore ereports for checksum errors generated by
* scrub/resilver I/O to avoid potentially further
* degrading the pool while it's being repaired.
*/
if (((nvlist_lookup_uint32(nvl,
FM_EREPORT_PAYLOAD_ZFS_ZIO_PRIORITY, &pri) == 0) &&
(pri == ZIO_PRIORITY_SCRUB ||
pri == ZIO_PRIORITY_REBUILD)) ||
((nvlist_lookup_int32(nvl,
FM_EREPORT_PAYLOAD_ZFS_ZIO_FLAGS, &flags) == 0) &&
(flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER)))) {
fmd_hdl_debug(hdl, "ignoring '%s' for "
"scrub/resilver I/O", class);
return;
}

if (zcp->zc_data.zc_serd_checksum[0] == '\0') {
zfs_serd_name(zcp->zc_data.zc_serd_checksum,
pool_guid, vdev_guid, "checksum");
Expand Down

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