Vince Spinelli wrote:
Hello,
My name is Vince Spinelli, from Buffalo, NY (US). I am currently using
'mdadm' under Fedora Core 5 (32-bit) to run two Soft-RAID arrays.
1) RAID-1 (mirror) for mission critical data. #drives = 2 ea. PATA ATA100
2) RAID-5 (striped+parity) for multimedia data. #drives = 5 ea. SATA 3G
My question is this...
In case of catastropic machine failure, such as the operating system
(which is on a separate PATA ATA100 drive) failing or even the OS hard
drive being physically destroyed, how would I go about rebuilding my RAID
arrays?
May I say that if you don't want to lose your data, then the o/s is
"critical data." I regard boot, root, and swap as critical, because if
they fail you have a much more complex recovery issue. Also note that
you still need backup, because some hardware failure modes will write
bad data (maybe silently) without an actual "crash" you notice. Power
supplies, controllers, and disk drives will help you test your backup
procedures.
Obviously, this would assume that the 7 disks which make up my arrays had
survived and were not damaged.
-I would obviously then build a new computer,
-install Linux, make sure 'mdadm' was installed,
-physically install all of my drives into the computer,
-copy my old /etc/mdadm.conf file (which has been saved on cd-rom but is
easily re-made) onto the new computer,
- and then what?
I have thought about this, and I can't understand how 'mdadm' decides the
health of an array.
For example, if I type at prompt:
/sbin/mdadm --detail /dev/md1
then I am given the current status of array 'md1'. It may be clean,
degraded, recovering, or whatever. Therefore, on a fresh install of
Linux, with a fresh copy of 'mdadm', I am led to believe that the result
of the previous command would be something like...
Active Devices = 0
Working Devices = 4
Failed Devices = 0
Spare Devices = 4
That, obviously would be no good.
So, please, if anyone has rebuilt a Soft-RAID array from scratch WHILE
STILL PRESERVING THE DATA ON THAT ARRAY with 'mdadm', please explain how
this is accomplished, as I'm sitting on 1.5 TB of data that I truly do not
want to lose.
You just set devices to PARTITIONS and use the -assemble command. Oh,
you use a superblock with uuid so assemble can figure out what to do.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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