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== Write-intent bitmaps ==

[[https://raid.wiki.kernel.org/index.php/Bitmap|Write-intent bitmaps]] speed-up RAID resyncs significantly, at the expense of a little write performance.

{{{#!highlight sh
# Create write-intent bitmap
mdadm --grow --bitmap=internal /dev/mdX

# Remove write-intent bitmap
mdadm --grow --bitmap=none /dev/mdX

Creation

   1 # RAID 5 array creation
   2 sudo mdadm --create /dev/md5 --level=5 --raid-devices=3 /dev/sd[def]1
   3 
   4 # Create a high-performance RAID10 array (2x read speed compared to RAID1)
   5 sudo mdadm --create /dev/md6 --level=10 -p f2 --raid-devices=2 /dev/sd[ik]1

Write-intent bitmaps

Write-intent bitmaps speed-up RAID resyncs significantly, at the expense of a little write performance. 

   1 # Create write-intent bitmap
   2 mdadm --grow --bitmap=internal /dev/mdX
   3 
   4 # Remove write-intent bitmap
   5 mdadm --grow --bitmap=none /dev/mdX

Diagnosis

Examine array component

Displays superblock information, including last event, RAID UUID, other components, etc. 

   1 mdadm --examine /dev/sda1

CategoryCheatSheet

SamatsWiki: CheatSheet/LinuxSoftwareRAID (last edited 2021-11-01 21:59:06 by SamatJain)