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Show software RAID (mdadm) status

harmlessSystem and hardwaredebian, ubuntu
user@server
cat /proc/mdstat

Lists each array such as md0 with RAID level and members. The key part is in square brackets: [UU] means both disks are active, [U_] means a failed mirror. During a rebuild, a progress bar with remaining time appears.

Note: Applies only to Linux software RAID. Hardware RAID controllers need the vendor’s tool.

Also searched as

  • is my raid ok
  • check raid degraded
  • show raid rebuild progress

Related one-liners

All in System and hardware

Show details of a software RAID array

#mdadm --detail /dev/md0
harmlessSystem and hardware

Check the SMART health status of a disk

#smartctl -H /dev/sda
harmlessSystem and hardware

Show SMART attributes of a disk

#smartctl -A /dev/sda
harmlessSystem and hardware

Start a SMART short self-test on a disk

#smartctl -t short /dev/sda
harmlessSystem and hardware

List disks and partitions

$lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINT,UUID
harmlessFilesystem

Change swappiness at runtime

#sysctl vm.swappiness=10
cautionSystem and hardware

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