Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++)

[Chris Snook <csnook@xxxxxxxxxx>]

Jens Bäckman wrote:
> On Wed, May 28, 2008 at 10:53 AM, Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote:
> > Results:
> >
> > http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html
> > http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt
>
> Either the RAID 1 read speed must be wrong, or something is odd in the
> Linux implementation. There's six drives that can be used for reading
> at the same time, as they contain the very same data. 63MB/s
> sequential looks like what you would get from a single drive.

The test is a single thread reading one block at a time, so this is not 
surprising.  If you get this doing multi-megabyte readahead, or with 
several threads, something is very wrong.

-- Chris