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Defer resilver only when progress is above a threshold 

Restart a resilver from scratch, if the current one in progress is
below a new tunable, zfs_resilver_defer_percent (defaulting to 10%).

The original rationale for deferring additional resilvers, when there is
already one in progress, was to help achieving data redundancy sooner
for the data that gets scanned at the end of the resilver.

But in case the admin wants to attach multiple disks to a single vdev,
it wasn't immediately obvious the admin is supposed to run
`zpool resilver` afterwards to reset the deferred resilvers and start
a new one from scratch.

Signed-off-by: Pavel Snajdr <snajpa@snajpa.net>
This commit is contained in:
Pavel Snajdr 2024-01-23 19:16:10 +01:00
parent af4da5ccf2
commit f8b3efbf30
2 changed files with 39 additions and 6 deletions
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7
man/man4/zfs.4
View File

@ -1797,6 +1797,13 @@ Ignore the
feature, causing an operation that would start a resilver to
immediately restart the one in progress.
.
.It Sy zfs_resilver_defer_percent Ns = Ns Sy 10 Ns | Ns % Pq uint
If the ongoing resilver progress is below this threshold, a new resilver will
restart from scratch instead of being deferred after the current one finishes,
even if the
.Sy resilver_defer
feature is enabled.
.
.It Sy zfs_resilver_min_time_ms Ns = Ns Sy 3000 Ns ms Po 3 s Pc Pq uint
Resilvers are processed by the sync thread.
While resilvering, it will spend at least this much time

38
module/zfs/dsl_scan.c
View File

@ -212,6 +212,9 @@ static uint64_t zfs_max_async_dedup_frees = 100000;
/* set to disable resilver deferring */
static int zfs_resilver_disable_defer = B_FALSE;
/* Don't defer a resilver if the one in progress only got this far: */
static uint_t zfs_resilver_defer_percent = 10;
/*
* We wait a few txgs after importing a pool to begin scanning so that
* the import / mounting code isn't held up by scrub / resilver IO.
@ -4260,19 +4263,39 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
dsl_scan_t *scn = dp->dp_scan;
spa_t *spa = dp->dp_spa;
state_sync_type_t sync_type = SYNC_OPTIONAL;
if (spa->spa_resilver_deferred &&
!spa_feature_is_active(dp->dp_spa, SPA_FEATURE_RESILVER_DEFER))
spa_feature_incr(spa, SPA_FEATURE_RESILVER_DEFER, tx);
uint64_t to_issue, issued;
int restart_early;
/*
* Check for scn_restart_txg before checking spa_load_state, so
* that we can restart an old-style scan while the pool is being
* imported (see dsl_scan_init). We also restart scans if there
* is a deferred resilver and the user has manually disabled
* deferred resilvers via the tunable.
* deferred resilvers via the tunable, or if the curent scan progress
* is below zfs_resilver_defer_percent.
*/
if (dsl_scan_restarting(scn, tx) ||
/*
* Taken from spa_misc.c spa_scan_get_stats():
*/
to_issue = scn->scn_phys.scn_to_examine - scn->scn_phys.scn_skipped;
issued = scn->scn_issued_before_pass + spa->spa_scan_pass_issued;
/*
* Make sure we're not in a restart loop and check the threshold
*/
restart_early = spa->spa_resilver_deferred &&
!dsl_scan_restarting(scn, tx) &&
(issued < (to_issue * zfs_resilver_defer_percent / 100));
/*
* Only increment the feature if we're not about to restart early
*/
if (!restart_early && spa->spa_resilver_deferred &&
!spa_feature_is_active(dp->dp_spa, SPA_FEATURE_RESILVER_DEFER))
spa_feature_incr(spa, SPA_FEATURE_RESILVER_DEFER, tx);
if (dsl_scan_restarting(scn, tx) || restart_early ||
(spa->spa_resilver_deferred && zfs_resilver_disable_defer)) {
pool_scan_func_t func = POOL_SCAN_SCRUB;
dsl_scan_done(scn, B_FALSE, tx);
@ -5258,6 +5281,9 @@ ZFS_MODULE_PARAM(zfs, zfs_, scan_report_txgs, UINT, ZMOD_RW,
ZFS_MODULE_PARAM(zfs, zfs_, resilver_disable_defer, INT, ZMOD_RW,
"Process all resilvers immediately");
ZFS_MODULE_PARAM(zfs, zfs_, resilver_defer_percent, UINT, ZMOD_RW,
"Issued IO percent complete after which resilvers are deferred");
ZFS_MODULE_PARAM(zfs, zfs_, scrub_error_blocks_per_txg, UINT, ZMOD_RW,
"Error blocks to be scrubbed in one txg");
/* END CSTYLED */