Date: Fri, 31 Mar 2000 04:51:01 +0200 From: "Niels Chr. Bank-Pedersen" <ncbp@bank-pedersen.dk> To: Greg Lehey <grog@lemis.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Can one do a striped volume with mirrored plexes Message-ID: <20000331045100.A50664@bank-pedersen.dk> In-Reply-To: <20000331111613.A6178@mojave.worldwide.lemis.com>; from grog@lemis.com on Fri, Mar 31, 2000 at 11:16:13AM %2B1000 References: <20000330165535.C48576@bank-pedersen.dk> <20000331111613.A6178@mojave.worldwide.lemis.com>
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On Fri, Mar 31, 2000 at 11:16:13AM +1000, Greg Lehey wrote:
> On Thursday, 30 March 2000 at 16:55:35 +0200, Niels Chr. Bank-Pedersen wrote:
> > Hi,
> >
> > I have 3 Kingston DS-500 chassis' connected to 3 Tekram controllers,
> > and I want to create one volume/filesystem that must be resilient to
^^^
> > disk failure, chassis failure and controller failure.
> >
> > In vinum(8) it says that I can create a mirrored volume with two
> > striped plexes, but that would only give me resilience against disk
> > failure, so what I was thinking of was something like this:
> >
> > Chassis disks controller
> >
> > A 0 1 3 4 6 7 9 a x I
> > B 0 2 3 5 6 8 9 b x II
> > C 1 2 4 5 7 8 a b x III
> >
> > - where each number, 0-b (x being spare disks), represents a small
> > mirror of 2 disks, and then all mirrors should be striped together
> > to form one volume.
> >
> > With the above setup I believe I will have resilience
> > against all "single-unit failures" - be it disk, chassis or
> > controller, but I dont see any way to configure this with
> > vinum.
>
> Hmm. If I understand what you want here, this would do it:
>
> drive 0A device /dev/chassisA/drive0
> drive 1A device /dev/chassisA/drive1
> drive 2A device /dev/chassisA/drive2
> drive 3A device /dev/chassisA/drive3
> drive 4A device /dev/chassisA/drive4
> drive 5A device /dev/chassisA/drive5
> drive 6A device /dev/chassisA/drive6
> drive 7A device /dev/chassisA/drive7
> drive 8A device /dev/chassisA/drive8
> drive 0B device /dev/chassisB/drive0
> drive 1B device /dev/chassisB/drive1
> drive 2B device /dev/chassisB/drive2
> drive 3B device /dev/chassisB/drive3
> drive 4B device /dev/chassisB/drive4
> drive 5B device /dev/chassisB/drive5
> drive 6B device /dev/chassisB/drive6
> drive 7B device /dev/chassisB/drive7
> drive 8B device /dev/chassisB/drive8
> drive 0C device /dev/chassisC/drive0
> drive 1C device /dev/chassisC/drive1
> drive 2C device /dev/chassisC/drive2
> drive 3C device /dev/chassisC/drive3
> drive 4C device /dev/chassisC/drive4
> drive 5C device /dev/chassisC/drive5
> drive 6C device /dev/chassisC/drive6
> drive 7C device /dev/chassisC/drive7
> drive 8C device /dev/chassisC/drive8
> volume 0
> plex org striped 512k
> sd len 0b drive 0A
> sd len 0b drive 0B
> volume 1
> plex org striped 512k
> sd len 0b drive 0C
> sd len 0b drive 1A
>
> (etc).
I'm not sure I get this (or else I wasn't being clear about what
I want in the first place): Wouldn't this give me 12 seperate
volumes => 12 mountpoints (with the last 3 drives excluded)?
- And if I ommit all but the first volume statement like:
volume 0
plex org striped 512k
sd len 0b drive 0A
sd len 0b drive 0B
plex org striped 512k
sd len 0b drive 0C
sd len 0b drive 1A
(etc).
then it is my understanding that I would get one volume mirrored
on 12 plexes (8, I believe, is the maximum number allowed).
Hmm, probably me missing something obvious here.
> > I guess I can run vinum on top of vinum, but I don't know how well
> > that would perform, so has anyone tried something similar, or has
> > suggestions as to how to achieve both the resilience from mirroring
> > and the performance from striping with a setup like this?
>
> That way madness lies.
>
> Greg
> --
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/Niels Chr.
--
Niels Christian Bank-Pedersen, NCB1-RIPE.
Network Manager, Tele Danmark NET, IP-section.
"Hey, are any of you guys out there actually *using* RFC 2549?"
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