Re: RAID 0+1 OR 1+0 ?

Art S. Kagel said >RAID 0+1 (ie mirroring two stripe sets to each other): >If a drive fails one side of the mirror, an entire stripe set is useless >and the whole stripe needs to be recovered from mirror. Also you can >only recover from multiple drive failures if all failed drives are on >the same side of the mirror. (Probability of data loss from multiple >drive failure is 50%.) It's worse. If you have two mirrors A and B and a drive fails in A then any failure in B is catastrophic. However, you've lost a drive from A already so there are now more drives in B than a - so the odds of a second failure being catastrophic are *more* than 50%. Mike -- .----------------------------------------------------------------------. | Mike Jagdis | Internet: mailto:mike@roan.co.uk | | Roan Technology Ltd. | | | 54A Peach Street, Wokingham | Telephone: +44 118 989 0403 |