2 out of 5 drives in SHR being very busy

[mcdull]

I have a VM under Proxmox running DSM 6.2 with AMD cpu.

The DSM was migrated from an old intel with an SHR consists of 5 disks

3 x 8TB and 2 x 4TB

 

Occassionally, the 2 4TB disk will be extremely busy with utilization at 99-100%, while the other 3 at 60-65%

the 4TB disk are 7200 Toshiba, and the 8TBs are all helium based 5400rpm from WD.

 

Are there any means that I can check what the 2 4TB are actually doing?  I have scanned the 2 disks and without errors.

[mcdull]

/proc/mdstat 

 

Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] 
md2 : active raid5 sdk5[6] sdh5[4] sdl5[7] sdg5[8] sdj5[5]
      15608749824 blocks super 1.2 level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]
      [===============>.....]  resync = 75.9% (2961953688/3902187456) finish=127.9min speed=122511K/sec
      
md4 : active raid1 sdk6[0] sdl6[1]
      3906998912 blocks super 1.2 [2/2] [UU]
      
md5 : active raid1 sdi3[0]
      9761614848 blocks super 1.2 [1/1]
      
md1 : active raid1 sdg2[2] sdh2[5] sdi2[1] sdj2[4] sdk2[3] sdl2[6]
      2097088 blocks [12/6] [_UUUUUU_____]
      
md0 : active raid1 sdg1[4] sdh1[3] sdi1[5] sdj1[6] sdk1[1] sdl1[2]
      2490176 blocks [12/6] [_UUUUUU_____]
      
unused devices: <none>

[Mincemeat]

Performance difference thats all i think.