Dave Howorth wrote:
Per Jessen wrote:
Even with hot spares, the array will be running degraded until it's fully synced. With terabyte size disks, a resync can take quite a while = window for disaster if a 2nd disk break.
Right. RAID 5 is not a good idea with big disks. RAID 6 is better if the hardware is capable of it. Otherwise mdadm RAID 10 seems like a good compromise.
------ I disagree. 1) RAID is no substitute for regular backups. 2) RAID 6 even in hardware created a noticeable penalty, while RAID5 gets close to RAID0 speeds on READS and most WRITES. IF you have enough disks to do RAID 10, then you probably have enough to do 1 RAID5 and a another RAID5 dedicated to backup storage. Using tower of hanoi rotation one can minimize space for daily backups while requiring at most 4-5 restores from separate sources to bring up to the latest day (usually 2-3). FWIW, I use a RAID-50 3RAID5's (4data+3par) in a RAID0 + 1 spare. I figure statistically a RAID5 with 4 data discs is about the limit of safety for RAID5, but with 2-3TB /HD .. I very much sympathize with SUSE... been there, had this happen -- and I was the one who killed the 2nd disk (on trying to replace the faulty one, of course counted from wrong direction...me<==*bang*) -- all downloaded/internet content. 5-6T...*ouch* Only 1 6T volume with downloaded material wasn't regularly backed up (don't have the space for more than a duplicate and that's tight). Rest of system is backed up with dump/restore (xfs). But starting out, it was just downloaded stuff...thought I could always D/l it again...but at some point... *ouch*... it got past a size I wanted to D/l again. I learned...fortunately it was d/l'able stuff, so most was recoverable and my system disk and main server shares for serving local material to my PC(s) is fully backed up. The backups are on a separate set of disks...though sharing same enclosure...(ouch)... Anyway, bad things happen once in a while...I still don't think RAID6 is worth the overhead for as often as this type of thing happens. If you were a bank? Yeah..sure... but Open suse doesn't need 5-9's of uptime (99.999%) -- that's a reason for mirrors... (FWIW, I don't know of anyone who keeps regular backups like me...I'm a bit paranoid)...few companies do either I would note -- unless they have dedicated IT departments...which I doubt Opensuse has given they are an open source company -- they really have alot of dedicated IT staff in my limited experience. ;-(....). Condolences... -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org