Mar 18, 2020 · A scrub operation will read ALL data, both primary and parity data. So if you are resilvering a mirror or raidz1, they are equivalent as resilver has to read all the surviving data. If you are resilvering a 3-way mirror, raidz2 or raidz3, resilver will not read all of the surviving data, so in those cases, scrub and resilver are not equivalent.

Feb 8, 2019 · The scrub will give them a chance to correct any CKSUM errors lurking sooner than if you waited until you read them. If you don't have any "redundancy" between the virtual disks you've fed the zpool, you could argue there's not much point in scrubbing, since the scrub can't repair anything anyway.

Aug 18, 2023 · A “scrub” is when ZFS scans the data on a pool. Scrubs identify data integrity problems, detect silent data corruptions caused by transient hardware issues, and provide early disk failure alerts. Edit Default Scrub Tasks

Oct 6, 2021 · Schedule a scrub via cron. Edit your cronfile with the following command: sudo crontab -e. Add a line like the following: 0 2 20 */2 * /sbin/zpool scrub theNameOfYourPool. You can use crontab.guru to build your desired schedule.

Aug 6, 2022 · SMR disks are not recommend for use with ZFS, since when ZFS rebuilds (resilvers) data during the replacement of a failed disk, it will be ~15x slower to rebuild the data onto an SMR disk compared to CMR. If you had a CMR array that takes 6h to resilver a failed disk, then a comparable SMR array would take nearly 4 days to resilver a new disk.

Sep 17, 2020 · So reduced scrub speed with a maintained low load, that's exactly what I wanted. These are the values I used in /etc/modprobe.d/zfs.conf: options zfs zfs_scan_idle=5000 options zfs zfs_scrub_delay=200 options zfs zfs_scrub_min_time_ms=100 options zfs zfs_top_maxinflight=2

Jul 11, 2024 · TrueNAS needs at least one data pool to create scrub task. To create a scrub task for a pool, go to Data Protection and click ADD in the Scrub Tasks window. Select a preset schedule from the dropdown list or click Custom to create a new schedule for when to run a scrub task. Custom opens the Advanced Scheduler window. Advanced Scheduler

Jun 12, 2020 · Posted by u/jsalas1 - 10 votes and 7 comments

Jun 7, 2013 · When the scrub is done, if bad data was found and discarded a resilvering operation is triggered. This restores redundancy to an array (mirror, raidz, etc). Since the scrub triggers this behavior, you could call it part of the same operation, but …

Jan 15, 2021 · Pre-0.8.x scrubs by traversing all metadata and data, as they are layed out on disks. This causes many seeks that kills performance on mechanical disks. If used with low-perf 5K RPM disks filled with millions of small files, this means very long scrub/resilver times. With these older ZFS versions, you can tune some ZFS tunables; for example: