Rebuild Speed

1. Log in to the SSH console and then switch to the root user

   sudo -i
   

2. Check the current raid rebuild status

   cat /proc/mdstat
   

   Example output:

   root@Conan-NAS:~# cat /proc/mdstat
   Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
   md2 : active raid5 sda3[4] sdd3[3] sdc3[2] sdb3[1]
       11706589632 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/3] [_UUU]
       [============>........]  recovery = 61.7% (2408710916/3902196544) finish=3167.3min speed=7858K/sec
   
   md1 : active raid1 sda2[0] sdb2[1] sdc2[2] sdd2[3]
        2097088 blocks [4/4] [UUUU]
   
   md0 : active raid1 sda1[0] sdb1[1] sdc1[2] sdd1[3]
        2490176 blocks [4/4] [UUUU]
   
   unused devices: <none>
   

3. Raise the minimum speed by running

   echo 30000 > /proc/sys/dev/raid/speed_limit_min
   

4. Increase the stripe cache size for the specified partition

   echo 16384 >/sys/block/md2/md/stripe_cache_size