svn commit: r201658 - head/sbin/geom/class/stripe

[Ivan Voras]

2010/1/6 Alexander Motin <mav at freebsd.org>:
> Author: mav
> Date: Wed Jan  6 17:12:18 2010
> New Revision: 201658
> URL: http://svn.freebsd.org/changeset/base/201658
>
> Log:
>  Increase default block size from 4K to 64K. It was reduces 6 yeard ago,
>  when trees were big and FAST mode was enabled by default.
>
>  So small block size doesn't benefits linear I/O operations in FAST and
>  significantly slowdowns in ECONOMIC (default) mode. For single stream random
>  I/Os so small block doesn't give much benefits, as access time is usually
>  bigger then transfer time there. Same time it requires all heads to seek
>  together for every single request, reducing performance on parallel load.

I think there was one more reason - though I'm not sure if it is still
valid because of your current and future work - the MAXPHYS
limitation. If MAXPHYS is 128k, with 64k stripes data was only to be
read from maximum of 2 drives. With 4k stripes it would have been read
from 128/4=32 drives, though I agree 4k is too low in any case
nowadays. I usually choose 16k or 32k for my setups.