Date: Fri, 26 Feb 1999 10:13:59 -0500 From: Doug Ledford <dledford@redhat.com> To: Daniel.Veillard@w3.org Cc: "Robert G. Brown" <rgb@phy.duke.edu>, Maxwell Spangler <maxwell@clark.net>, AIC7xxx@FreeBSD.ORG Subject: Re: Adaptec 7890 and RAID portIII RAID controller Linux Support Message-ID: <36D6BA37.4571B7F7@redhat.com> References: <Pine.LNX.3.96.990225124113.3721A-100000@ganesh.phy.duke.edu> <36D5B02F.B9E0605C@redhat.com> <19990226080949.F29876@w3.org>
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Daniel Veillard wrote:
>
> > That's possible, but what I've found to be a good method is to do something
> > like this:
> >
> > /dev/sda1: 200MB
> > /dev/sda2: Rest of disk
> >
> > Then I copy that exact same paritioning to all the rest of the disks. When I
> > actually lay it out, /dev/sda1 becomes the self sustaining /boot partition and
> > /dev/sdb1, /dev/sdc1, /dev/sdd1, etc all become identical swap partitions that
> > are all set up with exactly the same priority level in the fstab. This way,
> > all the swap partitions end up being their own psuedo raid stripe, but they
> > bypass the VFS code and go directly into the block driver. They are also
>
> I have a problem with that: We are running here RAID 5 systems,
> the goal is to aproach 100% uptime as much as possible, hence RAID is
> used as a way to resist disk failures. If you stripes your swap space
> among those drives bypassing the redundancy layer from the RAID, you
> loose the ability to resist disk failures.
Fair enough, good point. I typically don't worry much about it since I don't
usually have swap in use (I've done plenty of the power a drive down and pull
it out of the array testing and I never had the swap space be an issue, it was
something I overlooked) and this was a brain fart on my part :)
>Especially with identical
> priorities, if you're using the swap even only a bit, taht mean that
> some dirty data owned by a running process will be on the failed drive
> and basically you will have to reboot to regain a functionning system.
> From a performance point of view, it looks silly to have swap running
> on top of RAID 5 (or even RAID 3) but this ensure that your system will
> stay up if one of the RAID'ed drives goes down.
I'm adding it to my archive for further refinement of the list I posted :)
--
Doug Ledford <dledford@redhat.com>
Opinions expressed are my own, but
they should be everybody's.
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