raid5 to raid6 - reshape very slow
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Hi Everyone,I'm currently reshaping my raid5 array into a raid6 array (by adding a spare and growing).
Unfortunately I didn't research the nuances before doing so and missed the opportunity to --layout=preserve.
As a result the array is rebuilding by use of a backup-file, at a rather slow pace.
md1 : active raid6 sde1 sdb1 sdh1 sdc1 sdg1 sdd1 sdf17325679680 blocks super 0.91 level 6, 64k chunk, algorithm 18 [7/6] [UUUUUU_] [=========>...........] reshape = 47.0% (689413888/1465135936) finish=4126.9min speed=3132K/sec
I have tried the following so far: * read ahead tweaking* stripe_cache_size tweaking (not a limiting factor - mdadm seems to tune this appropriately)
* running the backup file from dev/shm (only for testing purposes)The reshape does not seem to be IO or CPU bound, it just seems to be limited by the sync's and meta data updates to each disk.
Is it possible to increase the buffer/stripes that mdadm process in a batch to speed up the process (~41m/2 -> 1G) ?
Any thoughts would be appreciated (even to confirm there is nothing to be done).
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