Just wanted to add a few more details/questions to my previous post..
In case I provided too much information in my previous email, here's a
condensed version:
1) got to "step 6.2 Add the first-disk to our existing RAID device" of
the rootraiddoc walkthrough
2) issued command "mdadm --add /dev/md0 /dev/hda1"
3) after getting terrible throughput, decided to stop the
synchronization process and reboot
4) failed to reboot from /dev/md0 (hdc1)
5) hda1 is now hosed, hdc1 contains a complete working copy of the
previous contents of /dev/hda1, but I'm unable to boot from it
("ALERT! /dev/md0 does not exist" message)
6) re-installed debian onto hda1 and rebooted from it.
Now, it seems as though I'm sort of back at "step 3.3 Create RAID
device". I've tried to do the following while booted from my clean
debian install on /dev/hda1:
mkdir /mnt/md0
mount /dev/md0 /mnt/md0
but I get the message "mount: you must specify the filesystem type",
because I guess the system has no idea what /dev/md0 is. So then I
tried the following (possibly risky?) command:
mdadm --create /dev/md0 --level=1 --raid-disks=2 --spare-devices 0
missing /dev/hdc1
but I get the message:
mdadm: /dev/hdc1 appears to contain an ext2fs file system
size=158577472K mtime=Tue Apr 4 18:21:09 2006
mdadm: /dev/hdc1 appears to be part of a raid array:
level=1 devices=2 ctime=Mon Apr 3 13:41:33 2006
Continue creating array? n
mdadm: create aborted
It seems from the above message that mdadm --create would destroy all
the data on /dev/hdc1 (someone correct me if I'm wrong), rather than
simply creating /dev/md0. If this is the case, should I be using
mdadm --assemble instead? (but if so, I need to assemble to a
pre-existing md device, in which case I don't have one) What I'd like
to do is be able to mount /dev/hdc1 as /dev/md0 (as in "step 4.2 Mount
your RAID device."), and then hopefully be able to boot off of it, but
right now I'm confused about how to create /dev/md0 without destroying
any of my information on either /dev/hda1 or /dev/hdc1 (of course,
after the reboot, I don't mind destroying /dev/hda1).
the other alternative is of course to zero the superblocks on
/dev/hdc1, reboot from it as a normal drive, and then follow the
walkthrough from the beginning, but this time starting with /dev/hdc1
as the master drive. I'd like to avoid this if possible, since I'd
really like to find out why I can't boot from /dev/md0 (hdc1), since
if this was not a test, and /dev/hda1 really did fail, I'd be in a
mess. So I'd prefer to know how to recover from this, since it seems
that the position I'm in right now is essentiallly the same scenario
as if /dev/hda1 had failed, in which case I'd like to be prepared.
If anyone can make heads or tails of what I'm talking about, I would
greatly appreciate any information or suggestions. Thanks in advance,
Mike
P.S. output of mdadm --examine is given below (output is the same for
/dev/hda1 and /dev/hdc1)
Magic : a92b4efc
Version : 00.90.03
UUID : f1ab0f6d:6c5c4bf6:228dec79:3aa3582f
Creation Time : Mon Apr 3 13:41:33 2006
Raid Level : raid1
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Update Time : Tue Apr 4 09:37:10 2006
State : clean
Active Devices : 1
Working Devices : 2
Failed Devices : 0
Spare Devices : 1
Checksum : f63c0eb5 - correct
Events : 0.19314
Number Major Minor RaidDevice State
this 1 22 1 1 active sync /dev/hdc1
0 0 0 0 0 removed
1 1 22 1 1 active sync /dev/hdc1
2 2 3 1 2 spare /dev/hda1
I'm in the process of setting up a software RAID level 1 on debian
testing with two 160 gig drives on an Asus P4P800 motherboard with
Intel Pentium 4 CPU 3.00GHz and 512 megs of RAM. I've been following
the instructions in /usr/share/doc/mdadm/rootraiddoc97.html, but after
rebooting to /dev/hdc1 (/dev/md0) and issuing the command "mdadm --add
/dev/md0 /dev/hda1", I was only getting 1636K/sec for the
synchronization, which was _way_ too slow (I forgot I had left a CDROM
drive on the secondary IDE channel, so /dev/hdc1 was running at UDMA2,
plus, I was using a 40 conductor cable instead of 80). So I decided
to reboot the system and cancel the synchronization, thus destroying
everything on /dev/hda1 (but this didn't seem like an issue, since I
was able to boot from /dev/md0 aka /dev/hdc1).
So after stopping the sync process and rebooting, I was unable to boot
from hdc1 because I had forgotten to copy over my initrd with md/raid1
modules from /dev/hda1 to /dev/hdc1, and of course now /dev/hda1 is
destroyed, so I can't use the initrd-RAID that was previously on there
(and the initrd-RAID never existed on /dev/hdc1, since I created it on
/dev/hda1 _after_ I had issued the "mount /dev/md0 /mnt/md0; cp -axu /
/mnt/md0" commands - don't ask why). So when I rebooted, I didn't
have md/raid1 support, and so /dev/md0 couldn't mount.. I ended up
building a new initrd with md/raid1 on another debian box, then
copying them to /dev/hdc1. I've now tried installing grub on
/dev/hdc, disconnected /dev/hda, and attempted to boot. I now get the
following message:
md: md driver 0.90.3 MAX_MD_DEVS=3D256, MD_SB_DISKS=3D27
md: bitmap version 4.39
md: raid1 personality registered as nr3
.
.
Begin: Mounting root file system...
Begin: Running /scripts/local-top
Done.
ALERT! /dev/md0 does not exist. Dropping to a shell!
At which point I get dropped into busybox.. One thing I notice is
that although it shows the md module being loaded, it doesn't really
say anything about configuring/adding any RAID disks (which is used to
say, back when I had first booted into /dev/md0 (hdc1) before killing
/dev/hda1). So now apparently /dev/md0 no longer exists, and I have
no idea how to create it.
In fstab on /dev/hcd1, I have:
/dev/md0 / ext3 defaults 0 0
and in /boot/grub/menu.lst I have:
title Debian GNU/Linux, kernel 2.6.15-486 RAID
root (hd0,0)
kernel /boot/vmlinuz-2.6.15-486 root=3D/dev/md0 ro
initrd /boot/initrd.img-2.6.15-486-RAID
savedefault
boot
Now, /dev/md0 was originally created by using:
mdadm --create /dev/md0 --level=3D1 --raid-disks=3D2 missing /dev/hdc1
can anybody tell me why /dev/md0 is no longer available on /dev/hdc1,
and if possible how to recreate it?
I should mention that after I cancelled the synchronization process,
and was unable to reboot into /dev/hdc1, I then mounted /dev/hdc1
through busybox, changed the Type of the disk from FD (linux raid) to
83 (linux), modified /etc/fstab and /boot/grub/menu.lst so it pointed
to /dev/hdc1 instead of /dev/md0. I tried rebooting after changing
these options, and it gave me a message saying "Failed to mount root
file system" or something to that effect. Could changing the Type of
the disk or mounting /dev/hdc1 have caused /dev/md0 to become
corrupted/deleted?
If anybody has the time to read through my message
and give me some advice, I would very much appreciate it. Thanks,
Mike
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