Jens Benecke wrote:
Yes you can do this - see last post, I prefer Grub, see the thread with the subject "GRUB + RAID howto" in the page linked below - I suggest trying both methods stated there, and testing which one works for you...How about RAIDing the root partition? If one drive fails will the other be able to boot via LILO? How about GRUB? Which do you prefer?
http://www.linuxsa.org.au/mailing-list/2003-07/thread.html
How about (/var)/tmp? I (suppose I'll) need it on both disks, does it make
sense to mirror it as well?
I would think so..
Can I mirror the whole disk? Or do I need to mirror each partition
seperately?
Each partition.
You will need to partition it, and use mdadm to add the new partitions to the array. But you can simply do something like this:Does MD or LVM2 do hot sync, i.e. if one drive fails will I be able to stick in a replacement, and stop worrying? Or do I need to repartition the new disk exactly as the old one, before being able to sync?
dd if=/dev/hda of=/dev/hdc ; echo w | fdisk /dev/hdc
How does LVM2/MD deal with failing harddisks, which is why I do the mirrorYou need to arrange to read check the drive (you probably want to do this on single drive systems as well) I would advise using smartmontools, (e.g. from Sarge), with these lines like these in /etc/smartd.conf (also comment out the DEVICESCAN line):
at all? I've heard about MD not detecting read errors because the "other"
disk was reading fine, and crashing completely when one disk was finally
replaced because the data on the other disk was also corrupt. Is that still
the current case?
/dev/hda -a -s L/../../6/01 -m root /dev/hdc -a -s L/../../6/02 -m root
This way you stand a better chance of catching blocks which are going bad before they become unreadable - it will ask the drives to carry out an extended self test (e.g. surface scan etc.) at 1am/2am on Saturday. Note that this will work with SCSI disks, PATA disks, and SATA disks which use the old IDE driver, but not yet with SATA disks using libata (you could make do with a "dd if=/dev/sda of=/dev/null" in a cron job instead).
On Debian, you should install the raidtools2 package, this will install a cron job which will email you on degraded array events (the smartd lines will email root on SMART errors as well) - but you should also install mdadm to use the new "mdadm" management tools. I would advise using Sarge, instead of Woody, unless you have a good reason not too...The goal is to have as "stress free" a system as possible - i.e. with as little manual configuration, and in event of emergencies, as little work to do, as possible.
Tim.
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