Disk I/O Performance

[Mike Horwath]

On Tue, Oct 19, 2004 at 04:45:03PM -0300, João_Carlos_Mendes_Luís wrote:
>     I'd say that you have to check which CCD chunk size is best for 
> your needs.  The manual for vinum recommends avoiding chunk sized to a 
> power of two, which is probably the first big mistake of everybody.
> 
>     Try mounting with option noatime, if you haven't already.  And use 
> the largest block size possible when formatting.  Last time I read about 
> there was a limit of 16384, but I would expect better performance for 
> large file with 64k blocks (and 8k frags).
> 
>     If you don't have a need for safety on the files, you could try 
> mount async and measure if it suits better you need for performance than 
> softupdates.  Sometimes softupdates is faster, and it is always safer.

All good ideas except the issue is bandwidth performance across the
disks.

I am seeing the same thing (and Kristofer and I have been working
together, kinda, on this).  It is as if I/O is being preferred for
writing vs reading, very weird.

His 5 disk stripe (well, it used to be five when I managed the
machine) should not have issues, but this recently begun happening
both on his systems and some of mine.

Very odd stuff...

-- 
Mike Horwath, reachable via drechsau at Geeks.ORG