No problems, I meant the driver for the hardward raid card does not work, it shows them up as 3 devices, rather than the one device which then goes on to cause problems with grub loading, this was a know problem on the dells which is why we went for feisty. Regards, Daniel
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Alan Pope Sent: 27 September 2007 13:49 To: British Ubuntu Talk Subject: Re: [ubuntu-uk] Software verses Hardware raid (was RE: Anyoneever tried kolab on feisty) Hi Daniel, On Thu, 2007-09-27 at 12:45 +0100, Daniel Lamb wrote: > Good arguments for it, I knew it was a very good system but never > looked at it in to great detail as we have always used cards as we use > linux and windows servers and like to keep the hardware quite alike. > It's worth a play even if you don't actually use it in anger. Nice to know that the feature is there. Maybe one day if you get time you could compare the two and make an informed decision about which is appropriate for your use. (hmm, that sounds more condescending that I intended, I just mean 'have a play' :) ) > I like the perc cards, prefer to set it all up before installs as I do not > want to accidentally lose data, > or does the linux software raid protect against you selecting the wrong > drivers and overwriting them? > When you say wrong drivers, I am not sure what you mean. When you setup Linux software raid devices you don't need additional drivers to make that work. So long as Linux can see the disks hanging off the controller there's nothing else to do other then configure each disk for RAID, and create the RAID multi-disk device. You'll then see (for example) a new device called /dev/md0 which might be an array of multiple disks. I use Linux software RAID on my main desktop PC:- Filesystem Size Used Avail Use% Mounted on /dev/md1 14G 2.4G 11G 18% / /dev/md3 215G 200G 4.0G 99% /home /dev/hda 513M 513M 0 100% /media/cdrom0 So you can see here that I have a 15G partition for / and a 215G partition for /home. md1 is made up of two RAID 1 partitions across /dev/sda and /dev/sdb, and so is md3. (md2 is my swap part). $ cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0] sdb2[1] 14843968 blocks [2/2] [UU] md2 : active raid1 sda1[0] sdb1[1] 1606400 blocks [2/2] [UU] md3 : active raid1 sda3[0] sdb3[1] 228661056 blocks [2/2] [UU] The [UU] means both disks in the array are available. The neat thing here is that I actually setup RAID 1 with only one disk, one missing. Then added the second disk later. So initially it showed as [U_] where the underscore indicates a missing disk. You can also do funky things like fail a disk out of the array:- # mdadm --manage /dev/md3 -f /dev/sdb3 mdadm: set /dev/sdb3 faulty in /dev/md3 # cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0] sdb2[1] 14843968 blocks [2/2] [UU] md2 : active raid1 sda1[0] sdb1[1] 1606400 blocks [2/2] [UU] md3 : active raid1 sda3[0] sdb3[2](F) 228661056 blocks [2/1] [U_] Note md3 now has one failed disk. Now I can remove it:- # mdadm --manage /dev/md3 -r /dev/sdb3 mdadm: hot removed /dev/sdb3 # cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0] sdb2[1] 14843968 blocks [2/2] [UU] md2 : active raid1 sda1[0] sdb1[1] 1606400 blocks [2/2] [UU] md3 : active raid1 sda3[0] 228661056 blocks [2/1] [U_] Neat! Lets add it back in again:- # mdadm --manage /dev/md3 --re-add /dev/sdb3 mdadm: re-added /dev/sdb3 And check the status of the mirror:- # cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0] sdb2[1] 14843968 blocks [2/2] [UU] md2 : active raid1 sda1[0] sdb1[1] 1606400 blocks [2/2] [UU] md3 : active raid1 sdb3[2] sda3[0] 228661056 blocks [2/1] [U_] [>....................] recovery = 0.1% (241600/228661056) finish=47.2min speed=80533K/sec Groovy. It's now recovering by resyncing sdb3 and sda3. Can you see I like software RAID :) Cheers, Al. -- ubuntu-uk@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk https://wiki.kubuntu.org/UKTeam/