Как определить оптимальный размер журнала для RAID-массива?

testserver ~ # cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid6 sdc[0] sdb[4] sdf[3] sde[2] sdd[1]
      5860540224 blocks level 6, 64k chunk, algorithm 2 [5/5] [UUUUU]
      bitmap: 0/233 pages [0KB], 4096KB chunk, file: /mnt/pciessd/mdadm_write_intent_bitmap
unused devices: <none>

testserver ~ # man mdadm | grep bitmap-chunk -A 7
--bitmap-chunk=
   Set the chunksize of the bitmap. Each bit corresponds to that many Kilobytes of storage.
   When using a file based bitmap, the default is to use the smallest size that is at-least 4
   and requires  no more than 2^21 chunks.  
   When using an internal bitmap,
   the chunksize is automatically determined to make best use of available space.