Re: raid question - failed
On Tue, 19 Aug 2003, Rudy Gevaert wrote:
> On Mon, Aug 18, 2003 at 01:18:39PM -0500, Patrick Albuquerque wrote:
>
> > A side-effect of using RAID-1 (mirroring) is that the partitions
> > can be accessed individually. This can be useful in case of emergency,
> > but you would not normally want to do this as your mirrors will get out
> > of sync.
>
> So if one disk fails I can take out the other disk and put in an other
> machine and mount the partitions? And everything should work?
yes .. that is the desired result... all depends on how you configured
your raid system from the very first command you invoked to build your
raid
it can be trivially simulated by disconnecting /dev/hda
and try to replace it with a blank disk ( preferably with fdisk already
done so that it helps the system along faster, more reliably )
- save your data before simulating a disk failure
http://www.1U-Raid5.net
if inserting a replacment disk didn't work, than raid was NOT configured
properly ... and is basically pointless
raid usually fails because of
- you need to use "FD" partition type
- you need to run lilo for "boot=/dev/md0" and root=/dev/md0 not
individual partitions /dev/hda1 etc ( same for grub )
- you need to make sure the drives are on different ide cables,
hda and hdc is best and no other disk on those cables
- if you are worried about data loss, do your normal daily incremental
backups as usual ...
- raid is NOT a backup solution
- raid might protect you against one disk failure, but not the 2nd
disk failure ... unless you have multiple preconfigured spare
disks
c ya
alvin
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