[GH-ISSUE #383] Feature: Add ability to speed up RAID Resyncs and Reshaping #848

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opened 2026-03-12 17:27:56 +03:00 by kerem · 0 comments

kerem commented

2026-03-12 17:27:56 +03:00

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Originally created by @madereddy on GitHub (Nov 12, 2024).
Original GitHub issue: https://github.com/007revad/Synology_HDD_db/issues/383

Originally assigned to: @007revad on GitHub.

Providing the ability to speed up RAID Resyncs and Reshaping would be very helpful. This gist has alot of details on it.

Add ability to capture the defaults for the following commands

cat /sys/block/md2/md/stripe_cache_size
cat /proc/sys/dev/raid/speed_limit_min
cat /sys/block/md2/queue/read_ahead_kb
cat /sys/block/md2/md/sync_max

Set new max values to help speed up the RAID operation

$ echo 32768 > /sys/block/md2/md/stripe_cache_size   # This is the max value, and it takes up 32Mib to synchronize read/write operations while the array is degraded
$ echo 50000 > /proc/sys/dev/raid/speed_limit_min    # This is a hint that you want more focus on the sync-expansion task
$ echo 32768 > /sys/block/md2/queue/read_ahead_kb    # This is how far ahead of a read request the drive array will preload
$ echo max > /sys/block/md2/md/sync_max

After RAID operation completes have a command to set the values back to the default captured in step 1.

Details on how much faster the RAID operation was by setting the different values in this gist comment.

Originally created by @madereddy on GitHub (Nov 12, 2024). Original GitHub issue: https://github.com/007revad/Synology_HDD_db/issues/383 Originally assigned to: @007revad on GitHub. Providing the ability to speed up RAID Resyncs and Reshaping would be very helpful. This [gist](https://gist.github.com/fbartho/2cb998dc1f10d13c124bf736286fd757) has alot of details on it. 1. Add ability to capture the defaults for the following commands ``` cat /sys/block/md2/md/stripe_cache_size cat /proc/sys/dev/raid/speed_limit_min cat /sys/block/md2/queue/read_ahead_kb cat /sys/block/md2/md/sync_max ``` 2. Set new max values to help speed up the RAID operation ``` $ echo 32768 > /sys/block/md2/md/stripe_cache_size # This is the max value, and it takes up 32Mib to synchronize read/write operations while the array is degraded $ echo 50000 > /proc/sys/dev/raid/speed_limit_min # This is a hint that you want more focus on the sync-expansion task $ echo 32768 > /sys/block/md2/queue/read_ahead_kb # This is how far ahead of a read request the drive array will preload $ echo max > /sys/block/md2/md/sync_max ``` 3. After RAID operation completes have a command to set the values back to the default captured in step 1. Details on how much faster the RAID operation was by setting the different values in this [gist comment](https://gist.github.com/fbartho/2cb998dc1f10d13c124bf736286fd757?permalink_comment_id=5279285#gistcomment-5279285).