Yes, rebuild time and overall data loss risk is worse with the RAID5 variants. I'd sooner do RAID6 than RAID50.
Plus, not all controllers that will support RAID5 will support RAID50. * * *ASB* *http://XeeMe.com/AndrewBaker* *Harnessing the Advantages of Technology for the SMB market… * On Thu, Dec 15, 2011 at 10:21 PM, Ben Scott <[email protected]> wrote: > On Thu, Dec 15, 2011 at 9:20 PM, Bill Humphries <[email protected]> > wrote: > > Seems everyone assumed RAID 10. Would you not consider > > RAID 50 if you had 8 SAS drives and decent controller with battery backed > > cache? > > (Sanity check: RAID 50 = RAID 0 of RAID 5's = stripe of > stripes-with-parity. You need at least three disks for RAID 5. So > with 8 disks, the only configuration that uses all of them would be > two 4-disk RAID 5 sets, then stripped with RAID 0. Yah?) > > My take is: > > With modern disk sizes, RAID 5 can be pretty horrible during a > rebuild. Say you've got 8 x 600 GB. 4 x 600 = 2400 GB, raw. Lose > one disk, replace it, and you have to read 1800 GB to rebuild that one > 600 GB missing member. > > And with the large disk sizes, the chances of a double failure are > higher, too. Sucks to find out there's a new bad block in that > remaining 1800 GB. > > RAID 10 is nice and simple: At most you're doing I or O on an entire > single disk. Plus it's much better in terms of I/O performance. Disk > usage efficiency is crap at 50%, but with the low cost of storage > these days, that's not as big a loss as it once was. And with only 8 > disks, RAID 50 is only going to be 75% efficient, right? > > -- Ben > > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to [email protected] with the body: unsubscribe ntsysadmin
