Subject: Re: 3ware RAID controller slow?
To: Jukka Marin <email@example.com>
From: Bill Stouder-Studenmund <firstname.lastname@example.org>
Date: 10/30/2007 08:49:01
Content-Type: text/plain; charset=us-ascii
On Mon, Oct 29, 2007 at 12:04:47AM +0200, Jukka Marin wrote:
> On Sun, Oct 28, 2007 at 10:55:53PM +0100, Michael van Elst wrote:
> > On Sun, Oct 28, 2007 at 10:50:31PM +0200, Jukka Marin wrote:
> > > No swap is in use, if that's what you mean. But no, 4 GB of RAM is n=
> > > enough to buffer 10 GB files.. :)
> > I guess this is the problem. When you run out of buffers then the
> > VM system and thus the file cache gets very slow.
> Then why is RAID5 slow and a plain disk isn't (when extracting the same
> pkgsrc tarball)? I'm trying to find out whether I can use RAID5 or not,
> that's why I'm asking ;)
What could be happening is that you're doing a lot of RMW operations when=
you write metadata. They are slow and add synchronous reads into important=
> (Although I need to find a way to break the 2 TB disklabel barrier first.=
Disklabels don't break 2 TB. That's why we have wedges.
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