Replacing disk in Linux Software RAID 1
Michael E. Webster
mwebster at intercosmos.com
Fri Aug 13 22:12:53 UTC 2004
Michael,
Probably - I went with "ghost" because I had a boot floppy handy.
The main thing is to get the MBR from that first drive - without it,
you're out of luck.
In software RAID, the MBR is only written to the first drive, which
really doesn't make sense. I would think that if you had the first
drive fail, you should be able to boot off the second one - IMHO.
Mike.
On Fri, 2004-08-13 at 18:10, Michael Mansour wrote:
> Hi Michael,
>
> Many thanks for the below, I'll try this process
> tonight.
>
> With the "Ghost", could I simply boot from a Live
> Rescue CD and use something like:
>
> # dd if=/dev/hdg of=/dev/hde
>
> where /dev/hde would be the new blank drive?
>
> Michael.
>
> --- "Michael E. Webster" <mwebster at intercosmos.com>
> wrote:
> > Michael,
> >
> > Whaddaya know.. I just happen to have a recipe for
> > doing this.
> > I went through a similar problem about two months
> > ago.
> > Just substitute /dev/hde and /def/hdg where
> > applicable.
> >
> >
> > Copy the MBR to /dev/hdc (done before procedure)
> >
> > prompt# grub
> >
> > Grub> device (hd0) /dev/hdc
> >
> > Grub> root (hd0,0)
> >
> > Grub> setup (hd0)
> >
> >
> > Make sure that we have the partition table for all
> > drives backed up
> > (done before)
> >
> > prompt# sfdisk -d /dev/hda >
> > /raidinfo/partitions.hda
> >
> > prompt# sfdisk -d /dev/hdc >
> > /raidinfo/partitions.hdc
> >
> > prompt# more /proc/mdstat > /raidinfo/mdstat.md
> >
> >
> > Estimated time: zero minutes
> >
> >
> > Shutdown the box
> >
> > Remove /dev/hda and label as â??hda badâ??
> >
> > Boot box to make sure it boots
> >
> > Shutdown server and place new blank drive in ide0
> > (new hda)
> >
> > Estimated time: ten minutes
> >
> >
> > Ghost ide1 (hdc) to ide0 (hda)
> >
> > Do â??Boot Imageâ?? copy
> >
> > Estimated time: a little more than an hour
> >
> >
> > Remove ide1 (original hdc) and label as â??hdc
> > goodâ??
> >
> > Power on to make sure ide0 (new hda) boots
> >
> > Shutdown and place new blank drive in ide1 (new hdc)
> >
> > Power on to make sure it boots
> >
> > Shutdown
> >
> > Estimated time: fifteen minutes
> >
> >
> > Power on and boot
> >
> > Copy the MBR to hdc
> >
> > prompt# grub
> >
> > Grub> device (hd0) /dev/hda
> >
> > Grub> root (hd0,0)
> >
> >
> >
> > Hope this helps,
> > Mike.
> >
> >
> >
> >
> > On Fri, 2004-08-13 at 17:51, Michael Mansour wrote:
> > > Hi,
> > >
> > > I have a server with a 2 disk Linux Software RAID
> > 1
> > > setup (two 80Gb disks). The first device is
> > /dev/hde
> > > and the second is /dev/hdg.
> > >
> > > The /dev/hde device is ready to fail, as it
> > produces
> > > various SMART errors using smartctl and fails on a
> > > self-test with:
> > >
> > > [root at gazelle root]# smartctl -l selftest /dev/hde
> > > smartctl version 5.30 Copyright (C) 2002-4 Bruce
> > Allen
> > > Home page is http://smartmontools.sourceforge.net/
> > >
> > > === START OF READ SMART DATA SECTION ===
> > > SMART Self-test log structure revision number 1
> > > Num Test_Description Status
> > > Remaining LifeTime(hours) LBA_of_first_error
> > > # 1 Short offline Completed: read failure
> >
> > > 90% 34 0x0463c0ee
> > > # 2 Short offline Completed: read failure
> >
> > > 90% 1087 0x0425290c
> > > # 3 Extended offline Completed: read failure
> >
> > > 90% 1072 0x0425290c
> > > # 4 Short offline Completed: read failure
> >
> > > 90% 1072 0x0425290c
> > > # 5 Short offline Completed: read failure
> >
> > > 90% 1071 0x0425290c
> > >
> > > The server is running Fedora Core 1.
> > >
> > > I have the new 80Gb disk and wish to replace
> > /dev/hde
> > > device with the new disk, how do I do this?
> > >
> > > The following is how I have the mirror setup:
> > >
> > > # fdisk -l /dev/hde
> > >
> > > Disk /dev/hde: 80.0 GB, 80026361856 bytes
> > > 255 heads, 63 sectors/track, 9729 cylinders
> > > Units = cylinders of 16065 * 512 = 8225280 bytes
> > >
> > > Device Boot Start End Blocks Id
> > > System
> > > /dev/hde1 * 1 395 3172806 b
> > > Win95 FAT32
> > > /dev/hde2 396 408 104422+ fd
> > > Linux raid autodetect
> > > /dev/hde3 409 1070 5317515 fd
> > > Linux raid autodetect
> > > /dev/hde4 1071 9729 69553417+ f
> > > Win95 Ext'd (LBA)
> > > /dev/hde5 1071 1331 2096451 fd
> > > Linux raid autodetect
> > > /dev/hde6 1332 1585 2040223+ fd
> > > Linux raid autodetect
> > > /dev/hde7 1586 1716 1052226 fd
> > > Linux raid autodetect
> > > /dev/hde8 1717 4327 20972826 fd
> > > Linux raid autodetect
> > > /dev/hde9 4328 9729 43391533+ fd
> > > Linux raid autodetect
> > >
> > > with /dev/hdg being exactly like above.
> > >
> > > As soon as I pull out the /dev/hde device, the
> > server
> > > won't boot (as grub only resides on /dev/hde), so
> > I
> > > also installed grub on /dev/hdg to overcome that
> > > problem. But now I'm wondering what I must do to
> > pull
> > > out /dev/hde and replace it with the new drive
> > (which
> > > doesn't have any partitioning setup) and then
> > force
> > > Linux to resync the data on /dev/hdg to the new
> > > /dev/hde?
> > >
> > > Is there some way I have to fail the /dev/hde
> > drive,
> > > replace it then put it back on-line? First time
> > I've
> > > done this with Software RAID so I'm not sure.
> > >
> > > Any advice is appreciated.
> > >
> > > Michael.
> > >
> > >
> > > Find local movie times and trailers on Yahoo!
> > Movies.
> > > http://au.movies.yahoo.com
> > >
> >
> >
> > --
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> >
> === message truncated ===
>
> Find local movie times and trailers on Yahoo! Movies.
> http://au.movies.yahoo.com
>
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