Re: [9fans] now for something completely devfs :)

[Fco.J.Ballesteros <nemo@plan9.escet.urjc.es>]

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if you have several partitions configure in devfs, them all are
updated. If you config the mirror before dding, then dd takes
care of everything not updated during the dd, and devfs takes
care of things updated while dding. Since devfs services reads
from the first device (as long as it works), there's no problem
in using it.

There's a race of course, but you can probably check later with cmp
(I did that a couple of times and the race did not hurt me). I'd try
as hard as feasible to keep the partitions untouched, just in case...

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From: andrey mirtchovski <mirtchov@cpsc.ucalgary.ca>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] now for something completely devfs :)
Date: Wed, 9 Jul 2003 11:19:46 -0600 (MDT)
Message-ID: <Pine.LNX.4.44.0307091113390.8525-100000@fbsd.cpsc.ucalgary.ca>

My fossil is working, but I still want to know if /dev/sdC0/fossil (for
example) changes while I'm dd-ing it to /dev/sdD0/fossil, will devfs take
care of that discrepancy?

The other question -- is there a way to know whether one or more of the
mirrored disks have crashed and take measures? Watch the HDD light on the
front panel? (A RAID controller we have here actually says that the only way
to know if a disk has crashed is to reboot the machine -- then the
controller BIOS will detect it.)

andrey

On Wed, 9 Jul 2003, Fco.J.Ballesteros wrote:

> I did setup the mirror before formatting venti/fossil partitions.
>
> Otherwise, you'd need to copy one disk to another while the partitions
> are idle.
>
> Let's say you have /dev/fs/mirror out of /dev/sdC0/part and /dev/sdC1/part
>
> If you add /dev/sdD0/part you could dd from either /dev/fs/mirror or
> from /dev/sdC[01]/part to /dev/sdD0/part. You should also add the device
> to devfs.
>
> I can help somehow, let me know.
>