On 09/13/2011 08:13 PM, George OLson wrote:
I have recently purchased a 1TB drive to use as the mirror image, with the intent that the 2nd 500GB on this drive will be used for other purposes, like maybe testing a new installation when it comes out, or just having extra data that I don't need on the mirror image partition. I have installed the 1TB drive and hooked it up. It is not yet partitioned.
I have done some research on the internet, and I found some tech sites that said that using the RAID setup in the BIOS is easy to set up, and you can do it without having to reinstall your OS. However, other sites have said that you do have to reinstall your OS, as it will wipe the original drive. (In any case, it would have been easier if I had set up RAID before the initial install, but too late now.)
You are correct - BIOS RAID is not an option if you want to save your current install. (unless you use dd to block copy your OS off to another spare drive, then install 2 [same size] drives, set up the bios raid, boot from the install cd and use dd to reinstall your OS onto the new mirror). Yes, you can mirror all partitions (/boot, /, /home & SWAP). I have run both BIOS RAID (dmraid) (called Fake RAID) and Linux Software RAID (mdraid). Both are great raid-1 solutions. Both have comparable performance (the software mirror demand on the system is negligible and you will not notice any performance hit with testparm benchmarks) You will have to get input from others on 'howto' create a software raid on the new disk from an existing install (I haven't done that). However, software raid is very flexible, so you may be able to do what you need without too much grief. In some respects software raid is a better solution. It is easier to move disks between boxes should you have that need. It is possible with dmraid, but it involves setting up a new pair of disks and then block copying from one of the drives onto the new array. Both will give you the single disk fault tolerance that RAID is designed to provide. In case of a disk failure, you can continue to run from either in 'degraded' (single disk) mode until you have replacement hardware. However - NEITHER dmraid or mdraid is a substitute for prudent BACKUPS. Any failure that will scatter the data on the array will happily scatter the data on both disks (controller or other hardware failure). So RAID isn't an excuse to not backup. Good luck. You will be satisfied with either solution. I use dmraid if I have a raid capable bios and software raid if I don't. That simple. I've been happy with both for the past decade. -- David C. Rankin, J.D.,P.E. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org