Score:0

Debian 10, very slow disk i/o, related to software raid

ru flag

Hey got a server here that's gotten very slow on disk i/o, mdstat mentions something about a check, but I can't find anything about that when googling for it. What is it doing here?

root@tynix /home/vintagestory/trailer/server # cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md2 : active raid1 sda4[0] sdb4[1]
      1073610560 blocks super 1.2 [2/2] [UU]
      [===================>.]  check = 99.4% (1067845568/1073610560) finish=1.6min speed=59370K/sec

md3 : active raid1 sda5[0] sdb5[1]
      1847478528 blocks super 1.2 [2/2] [UU]

md0 : active raid1 sdb2[1] sda2[0]
      8384448 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sda3[0] sdb3[1]
      523968 blocks super 1.2 [2/2] [UU]

unused devices: <none>
Score:1
za flag

It's checking the software array integrity by sequentially reading all of the sectors on each disk member. That's why the disk i/o is slow - iostat -xd 1 will probably show %busy at 99-100%.

Tyron avatar
ru flag
Thanks for the answer. Is that on a cronjob or whats the trigger for this?
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