On Wed Jul 29, 2009 at 11:25:47PM -0700, Tirumala Reddy Marri wrote:
> Hi,
> I have two 1 tera byte disks in RAID-1 configuration. When I started
> RAID-1 array initial speed was 100MBps by the time it finishes the speed
> was <50MBps. Is there is any reason for this behavior ? Isn't speed
> supposedly uniform.
>
No, the speed isn't uniform - it varies across the disk. The
_rotational_ speed is fixed (probably 7200 rpm), but that means the
outer tracks are passing at a higher _linear_ speed (i.e. in a single
rotation, there's more disk passing across the read head), so have a
higher transfer rate. Hard drives start writing from the outside, so
the speed drops off as you progress.
Cheers,
Robin
--
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( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
/ / ) | Little Jim says .... |
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