Re: Questions about RAID 6
On Wed April 28 2010 01:44:37 Stan Hoeppner wrote:
> On a sufficiently fast system that is not loaded, the user will likely see
> no performance degradation, especially given Linux' buffered I/O
> architecture. However, on a loaded system, such as a transactional
> database server or busy ftp upload server, such a RAID setup will bring the
> system to its knees in short order as the CPU overhead for each 'real' disk
> I/O is now increased 4x and the physical I/O bandwidth is increased 4x.
I've designed commercial database managers and OLTP systems.
If CPU usage had ever become a factor in anything I had designed
I would have been fired. If they're not I/O bound they're useless.
With a few exceptions such as physical backups, any I/O bound
application is going to be seek bound, not bandwidth bound.
--Mike Bird
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