Re: raid 1 recovery
hi ya
if raid1 mirroring is properly setup...
- make sure your partition types are all "FD" type
- what does your /etc/raidtab look like ?
the system WILL boot properly all by itself into /dev/hda or /dev/hdc
when one of the disk has failed
( simulate by pulling the power to it or the ide cable )
- you do NOT need tomsrtbt or any other standalone boot media
to fix one failed disk of a properly configured raid1
(mirror) system
- there is probably a misconfiguration someplace if your system
doesn't boot with just one disk ( of the 2 in the mirrored system)
-- first problem is to make sure the system keeps running even if a
disks died ... ( runs in degraded mode ... maybe use hdparm to shut the
drive down )
and that it is still bootable w/ any one of the two disks
-- resync is of the new disks is also done automatically
hotswapremove, hotswapadd combination of commands
while the system is resyncing, if you lose the 2nd disk, you're dead...
unless you start to manually build up the raid before it failed
with things like mdctl
c ya
alvin
On Sun, 13 Oct 2002, david hong wrote:
> there is a good article at linux journal about raid 1 setup
> http://www.linuxjournal.com/article.php?sid=5898&mode=thread&order=0
>
> I tested the suggested method, it works quite well.
> machine still boot up ok if any hdc partition fail.
>
> i tested many combinations of the failures, the difficult part
> is still the boot disk fails. I simulate it by unplug the cable from hda
> HD, while hdc still attach to my 2nd controller.
>
> the hdc root partition is a resync copy from the orginal date from hda,
> filesystem ext2.
>
> i boot up from tomsrtbt bootable floppy and amended the hdc /etc/fstab file
> to point to hdc instaed of hda.
> then i reboot it using a mkbootdisk floppy, and do a LILO:linux root=/dev/hdc1
> system boot up with all the superblock warnings....
>
> what is the fastest way to recover if bootdisk (hda) fail?
>
> (if did try move the hdc to primary controller, then i see
> superblock warnings again....)
>
>
>
> > with raid 0.90 it may be different, what does cat /proc/mdstat
> > show when you only have 1 disk?
> it display the default content. no md* active.
>
> David
>
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>
> On Fri, 11 Oct 2002 20:33:59 -0700 (PDT), nate wrote
> > david hong said:
> >
> > > if my hda (boot disk) fails, can i boot up from a
> > > mini bootable floppy and mount the hdc partition
> > > and recover the data?
> > >
> > > i tried that, but it keeps complaining filetype error
> > > when i try to mount the hdc partition.
> >
> > I haven't tried(or needed to) raid recovery with raid 0.90
> > but I have with raid 0.36(raid1). This uses normal linux partition
> > types instead of fd, one of my drives died and I switched
> > lilo and friends over to the seocnd disk, disabled raid and continued
> > to use the system for another few months till the 2nd disk died.
> >
> > with raid 0.90 it may be different, what does cat /proc/mdstat
> > show when you only have 1 disk? also be sure you have raid support
> > on that floppy, the new raid may "need" it to access the disk(perhaps
> > it is in a slightly different format which the raid tools provide
> > transparent access to).
> >
> > nate
> >
> > --
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