On Wed, Mar 27, 2013 at 12:11 PM, Stan Hoeppner [off-list ref] wrote:

On 3/27/2013 11:01 AM, Roy Sigurd Karlsbakk wrote:

quoted

From the manual

       -c, --chunk=
              Specify  chunk size of kibibytes.  The default when creating an array is 512KB.  To ensure compatibility with ear‐
              lier versions, the default when Building and array with no persistent metadata is 64KB.  This is  only  meaningful
              for RAID0, RAID4, RAID5, RAID6, and RAID10.

meaning - chunk size isn't relevant to a mirror

The man page should be changed to explicitly state that --chunk does not
apply to RAID1 or --linear arrays.  Far too many people are having
trouble with this.  For those people the current docs are apparently too
subtle.

--
Stan

'Subtle' is probably a good work. For me it took a few times reading
the man page after looking at what I have here where it tells me
nothing about chunk size on the RAID1.

Note that another level of understanding (which I don't have) has to
do with getting chunk sizes that work well for my needs. That's a
whole other kettle of fish...

Cheers,
Mark

mark@c2stable ~ $ cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md6 : active raid5 sdc6[1] sdd6[2] sdb6[0]
      494833664 blocks super 1.1 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
      bitmap: 0/2 pages [0KB], 65536KB chunk

md3 : active raid6 sdd3[2] sdc3[1] sdb3[0] sde3[3] sdf3[5]
      157305168 blocks super 1.2 level 6, 16k chunk, algorithm 2 [5/5] [UUUUU]

md7 : active raid6 sdd7[2] sdc7[1] sdb7[0] sde2[3] sdf2[4]
      395387904 blocks super 1.2 level 6, 16k chunk, algorithm 2 [5/5] [UUUUU]

md126 : active raid1 sdb5[0] sdd5[2] sdc5[1]
      52436032 blocks [3/3] [UUU]

unused devices: <none>
mark@c2stable ~ $
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