From c21c3b0befeb46a51b6bf3758ffa30813bea0ff0 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 9 Mar 2024 14:19:22 +0100 Subject: Adding upstream version 1.44.3. Signed-off-by: Daniel Baumann --- health/guides/mdstat/mdstat_disks.md | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 health/guides/mdstat/mdstat_disks.md (limited to 'health/guides/mdstat/mdstat_disks.md') diff --git a/health/guides/mdstat/mdstat_disks.md b/health/guides/mdstat/mdstat_disks.md new file mode 100644 index 000000000..c3daf9619 --- /dev/null +++ b/health/guides/mdstat/mdstat_disks.md @@ -0,0 +1,26 @@ +### Understand the alert + +This alert presents the number of devices in the down state for the respective RAID array raising it. If you receive this alert, then the array is degraded and some array devices are missing. + +### What is a "degraded array" event? + +When a RAID array experiences the failure of one or more disks, it can enter degraded mode, a fallback mode that generally allows the continued usage of the array, but either loses the performance boosts of the RAID technique (such as a RAID-1 mirror across two disks when one of them fails; performance will fall back to that of a normal, single drive) or experiences severe performance penalties due to the necessity to reconstruct the damaged data from error correction data. + +### Troubleshoot the alert + +- Examine for faulty or offline devices + +Having a degraded array means that one or more devices are faulty or missing. To fix this issue, check for faulty devices by running: +``` +mdadm --detail +``` +Replace "RAIDDEVICE" with the name of your RAID device. + +To recover the array, replace the faulty devices or bring back any offline devices. + +### Useful resources + +1. [Degraded Mode](https://en.wikipedia.org/wiki/Degraded_mode) +2. [Mdadm recover degraded array procedure](https://www.thomas-krenn.com/en/wiki/Mdadm_recover_degraded_Array_procedure) +3. [mdadm Manual page](https://linux.die.net/man/8/mdadm) +4. [mdadm cheat sheet](https://www.ducea.com/2009/03/08/mdadm-cheat-sheet/) \ No newline at end of file -- cgit v1.2.3