Personally I feel raids only real use is data protection, as hard drives are sometimes very unreliable anyway how is really worried about speed? This is in a server which means its not reading or writing at a very fast speed anyway.
Regards, Daniel -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matthew Larsen Sent: 27 September 2007 15:26 To: British Ubuntu Talk Subject: Re: [ubuntu-uk] Software verses Hardware raid (was RE: Anyone evertried kolab on feisty) I remember a test some magazine did with a Raid 0 with 2 10k SATAII Raptors: and only got something like a 2% performance increase. I would advise not using RAID for anything apart from redundancy. Regards, On 27/09/2007, Daniel Lamb <[EMAIL PROTECTED]> wrote: > 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. > > > -- > [email protected] > https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk > https://wiki.kubuntu.org/UKTeam/ > -- Matthew G Larsen > [EMAIL PROTECTED] > [EMAIL PROTECTED] -- [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk https://wiki.kubuntu.org/UKTeam/ -- [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk https://wiki.kubuntu.org/UKTeam/
