From: Andrew Walrond <andrew@walrond.org>
To: linux-kernel@vger.kernel.org
Subject: Re: Anybody know about nforce4 SATA II hot swapping + linux raid?
Date: Sat, 8 Oct 2005 17:03:32 +0100
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Cc: Gordon Henderson <gordon@drogon.net>, linux-raid@vger.kernel.org
References: <200510071111.46788.andrew@walrond.org> <200510081555.41159.andrew@walrond.org> <Pine.LNX.4.56.0510081600080.7326@lion.drogon.net>
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Hi Gordon,

On Saturday 08 October 2005 16:23, Gordon Henderson wrote:
> On Sat, 8 Oct 2005, Andrew Walrond wrote:
> > On Saturday 08 October 2005 15:26, Molle Bestefich wrote:
> > > IDE hotswap has never worked (OOTB at least) in Linux, and based on my
>
> Ideally you want hardware that will power the drive down nicely before you
> take it out (and power it up nicely after you plug it back in again) to
> avoid any glitches on the SCSI bus, etc...

Sounds hairy! Are you aware of any linux scsi drivers which support this 
powering up/down, via /proc or some userspace tools perhaps?

>
> One thing to watch out for - if you reboot after taking the drive out the
> scsi drive letters will be logically renumbered, so if you take out sda,
> then reboot, what was sdb will now become sda, and so on, so if you then
> subsequently hot plug a drive in, it will still have the same scsi host,
> channel, id, lun numbers, but it'll be the last device in the array (eg.
> it will be sdf if it was a 6-disk array) Reboot again and the original
> numbering/lettering would be restored.
>
> Good job the RAID code doesn't really care about this...

Indeed. Linux raid is very fine. If we can just fixup this hotplug weakness, 
it would be peerless.

>
> Good luck!
>

Thanks, and good to hear from you ;)

Andrew
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