Resilver restarts unnecessarily when it encounters errors
When a resilver finishes, vdev_dtl_reassess is called to hopefully excise DTL_MISSING (amongst other things). If there are errors during the resilver, they are tracked in DTL_SCRUB, as spelled out in the block comment in vdev.c. DTL_SCRUB is in-core only, so it can only be used if the pool was online for the whole resilver. This state is tracked with the spa_scrub_started flag, which only gets set when the scan is initialized. Unfortunately, this flag gets cleared right before vdev_dtl_reassess gets called, so if there are any errors during the scan, DTL_MISSING will never get excised and the resilver will just continually restart. This fix simply moves clearing that flag until after the call to vdev_dtl_reasses. In addition, if a pool is imported and already has scn_errors > 0, this change will restart the resilver immediately instead of doing the rest of the scan and then restarting it from the beginning. On the other hand, if scn_errors == 0 at import, then no errors have been encountered so far, so the spa_scrub_started flag can be safely set. A test has been added to verify that resilver does not restart when relevant DTL's are available. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Paul Zuchowski <pzuchowski@datto.com> Signed-off-by: John Poduska <jpoduska@datto.com> Closes #10291
This commit is contained in:
John Poduska
Tony Hutter
parent
a72ae9bf3d
commit
c161360dce
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@ -540,6 +540,22 @@ dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
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zfs_dbgmsg("new-style scrub was modified "
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"by old software; restarting in txg %llu",
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(longlong_t)scn->scn_restart_txg);
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} else if (dsl_scan_resilvering(dp)) {
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/*
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* If a resilver is in progress and there are already
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* errors, restart it instead of finishing this scan and
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* then restarting it. If there haven't been any errors
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* then remember that the incore DTL is valid.
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*/
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if (scn->scn_phys.scn_errors > 0) {
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scn->scn_restart_txg = txg;
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zfs_dbgmsg("resilver can't excise DTL_MISSING "
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"when finished; restarting in txg %llu",
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(u_longlong_t)scn->scn_restart_txg);
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} else {
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/* it's safe to excise DTL when finished */
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spa->spa_scrub_started = B_TRUE;
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}
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}
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}
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@ -881,7 +897,6 @@ dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
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"errors=%llu", spa_get_errlog_size(spa));
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if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
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spa->spa_scrub_started = B_FALSE;
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spa->spa_scrub_active = B_FALSE;
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/*
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@ -908,6 +923,12 @@ dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
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}
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spa_errlog_rotate(spa);
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/*
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* Don't clear flag until after vdev_dtl_reassess to ensure that
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* DTL_MISSING will get updated when possible.
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*/
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spa->spa_scrub_started = B_FALSE;
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/*
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* We may have finished replacing a device.
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* Let the async thread assess this and handle the detach.
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@ -2566,7 +2566,6 @@ vdev_dtl_should_excise(vdev_t *vd)
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spa_t *spa = vd->vdev_spa;
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dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
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ASSERT0(scn->scn_phys.scn_errors);
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ASSERT0(vd->vdev_children);
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if (vd->vdev_state < VDEV_STATE_DEGRADED)
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@ -2617,6 +2616,7 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
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if (vd->vdev_ops->vdev_op_leaf) {
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dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
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boolean_t wasempty = B_TRUE;
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mutex_enter(&vd->vdev_dtl_lock);
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@ -2626,6 +2626,18 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
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if (zfs_scan_ignore_errors && scn)
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scn->scn_phys.scn_errors = 0;
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if (scrub_txg != 0 &&
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!range_tree_is_empty(vd->vdev_dtl[DTL_MISSING])) {
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wasempty = B_FALSE;
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zfs_dbgmsg("guid:%llu txg:%llu scrub:%llu started:%d "
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"dtl:%llu/%llu errors:%llu",
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(u_longlong_t)vd->vdev_guid, (u_longlong_t)txg,
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(u_longlong_t)scrub_txg, spa->spa_scrub_started,
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(u_longlong_t)vdev_dtl_min(vd),
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(u_longlong_t)vdev_dtl_max(vd),
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(u_longlong_t)(scn ? scn->scn_phys.scn_errors : 0));
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}
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/*
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* If we've completed a scan cleanly then determine
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* if this vdev should remove any DTLs. We only want to
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@ -2662,6 +2674,14 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
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space_reftree_generate_map(&reftree,
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vd->vdev_dtl[DTL_MISSING], 1);
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space_reftree_destroy(&reftree);
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if (!range_tree_is_empty(vd->vdev_dtl[DTL_MISSING])) {
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zfs_dbgmsg("update DTL_MISSING:%llu/%llu",
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(u_longlong_t)vdev_dtl_min(vd),
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(u_longlong_t)vdev_dtl_max(vd));
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} else if (!wasempty) {
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zfs_dbgmsg("DTL_MISSING is now empty");
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}
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}
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range_tree_vacate(vd->vdev_dtl[DTL_PARTIAL], NULL, NULL);
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range_tree_walk(vd->vdev_dtl[DTL_MISSING],
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@ -797,7 +797,7 @@ tests = ['reservation_001_pos', 'reservation_002_pos', 'reservation_003_pos',
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tags = ['functional', 'reservation']
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[tests/functional/resilver]
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tests = ['resilver_restart_001']
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tests = ['resilver_restart_001', 'resilver_restart_002']
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tags = ['functional', 'resilver']
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[tests/functional/rootpool]
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@ -2,7 +2,8 @@ pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/resilver
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dist_pkgdata_SCRIPTS = \
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setup.ksh \
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cleanup.ksh \
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resilver_restart_001.ksh
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resilver_restart_001.ksh \
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resilver_restart_002.ksh
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dist_pkgdata_DATA = \
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resilver.cfg
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@ -0,0 +1,102 @@
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#!/bin/ksh -p
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#
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# CDDL HEADER START
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#
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# This file and its contents are supplied under the terms of the
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# Common Development and Distribution License ("CDDL"), version 1.0.
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# You may only use this file in accordance with the terms of version
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# 1.0 of the CDDL.
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#
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# A full copy of the text of the CDDL should have accompanied this
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# source. A copy of the CDDL is also available via the Internet at
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# http://www.illumos.org/license/CDDL.
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#
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# CDDL HEADER END
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#
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#
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# Copyright (c) 2020, Datto Inc. All rights reserved.
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#
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. $STF_SUITE/include/libtest.shlib
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. $STF_SUITE/tests/functional/resilver/resilver.cfg
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#
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# DESCRIPTION:
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# Testing resilver completes when scan errors are encountered, but relevant
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# DTL's have not been lost.
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#
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# STRATEGY:
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# 1. Create a pool (1k recordsize)
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# 2. Create a 32m file (32k records)
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# 3. Inject an error halfway through the file
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# 4. Start a resilver, ensure the error is triggered and that the resilver
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# does not restart after finishing
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#
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# NB: use legacy scanning to ensure scan of specific block causes error
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#
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function cleanup
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{
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log_must zinject -c all
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destroy_pool $TESTPOOL
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rm -f ${VDEV_FILES[@]} $SPARE_VDEV_FILE
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log_must set_tunable32 zfs_scan_legacy $ORIG_SCAN_LEGACY
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}
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log_assert "Check for resilver restarts caused by scan errors"
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ORIG_SCAN_LEGACY=$(get_tunable zfs_scan_legacy)
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log_onexit cleanup
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# use legacy scan to ensure injected error will be triggered
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log_must set_tunable32 zfs_scan_legacy 1
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# create the pool and a 32M file (32k blocks)
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log_must truncate -s $VDEV_FILE_SIZE ${VDEV_FILES[0]} $SPARE_VDEV_FILE
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log_must zpool create -f -O recordsize=1k $TESTPOOL ${VDEV_FILES[0]}
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log_must dd if=/dev/urandom of=/$TESTPOOL/file bs=1M count=32 > /dev/null 2>&1
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# determine objset/object
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objset=$(zdb -d $TESTPOOL/ | sed -ne 's/.*ID \([0-9]*\).*/\1/p')
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object=$(ls -i /$TESTPOOL/file | awk '{print $1}')
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# inject event to cause error during resilver
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log_must zinject -b `printf "%x:%x:0:3fff" $objset $object` $TESTPOOL
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# clear events and start resilver
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log_must zpool events -c
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log_must zpool attach $TESTPOOL ${VDEV_FILES[0]} $SPARE_VDEV_FILE
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log_note "waiting for read errors to start showing up"
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for iter in {0..59}
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do
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zpool sync $TESTPOOL
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err=$(zpool status $TESTPOOL | grep ${VDEV_FILES[0]} | awk '{print $3}')
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(( $err > 0 )) && break
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sleep 1
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done
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(( $err == 0 )) && log_fail "Unable to induce errors in resilver"
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log_note "waiting for resilver to finish"
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for iter in {0..59}
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do
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finish=$(zpool events | grep "sysevent.fs.zfs.resilver_finish" | wc -l)
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(( $finish > 0 )) && break
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sleep 1
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done
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(( $finish == 0 )) && log_fail "resilver took too long to finish"
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# wait a few syncs to ensure that zfs does not restart the resilver
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log_must zpool sync $TESTPOOL
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log_must zpool sync $TESTPOOL
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# check if resilver was restarted
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start=$(zpool events | grep "sysevent.fs.zfs.resilver_start" | wc -l)
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(( $start != 1 )) && log_fail "resilver restarted unnecessarily"
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log_pass "Resilver did not restart unnecessarily from scan errors"
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