On Friday 06 October 2006 17:30, Christian Spoo wrote: > I need to set up a RAID box of about 470GB disk space accessible via > GBit LAN. > > The whole thing should have good performance but must be reliable as > well. Which RAID mode would you recommend, 5, 0+1 or maybe any other? > How about the time needed for rebuilding such arrays in case of disk > failure?
Firstly, forget 0+1, use RAID10. Define "good performance". Reads or writes? RAID5 is fast for reads, slow for writes, and you lose the capacity of 1 disk. RAID10 is *fast* for reads *and* writes, but you lose the capacity of half your disks. RAID5 can live with the failure of one drive, but takes a large performance hit and all your redundancy is gone until a new one is synced up which is hard and time consuming to do. RAID10 can, in theory, lose half of the disks and continue with little to no slow down. Rebuilds are easier than RAID5 as it's a straight bit for bit copy. RAID6 adds a second disk worth of redundancy, but slows writes down further. As a bad benchmark I had to rebuild a 4 200GB disk RAID5 array the other evening on a P3 1400, took ~140minutes. On at least 2 occasions I've had another disk die while doing a RAID rebuild, the stress was too much for it, for this reason I won't use RAID5 again unless there is a very good reason for it (i.e. need for redundancy is minimal, and space is more important). -- Mike Williams -- [email protected] mailing list
