Failure, capacity and speed of various RAID types for 10 disks
Speed relative to 3-disk parity (P) or single disk (S), assuming striping
doubles virtual disk speed and mirroring halves it.
One may estimate that 1xP = 1.5xS.
| No-risk failures | Risk of next failure | Capacity | Speed
---------------------------------------------------------------------------
0 | 0 | 100 | 1 | 10S
1 | 9 | 100 | 1 | 1S
5 (6) | 2 | 100 | 4 | 1P (1.5S)
5 (6R) | 6 | 100 | 4 | 1P (1.5S)
0+1 | 1 | 56 | 2 | 5S
1+0 | 1 | 11 | 2 | 5S
0+5 (6) | 1 | 80 | 2 | 2SP (3S)
0+5 (6R)| 5 | 80 | 2 | 2SP (3S)
0+5 (9) | 1 | 75 | 2 | 3SP (4.5S)
0+5 (9R)| 2 | 75 | 2 | 3SP (4.5S)
5+0 (6) | 1 | 40 | 2 | 2SP (3S)
5+0 (6R)| 2 | 40 | 2 | 2SP (3S)
5+0 (9) | 1 | 25 | 2 | 3SP (4.5S)
5+0 (9R)| 2 | 25 | 2 | 3SP (4.5S)
Number in parentheses is number of disks in array. The rest are hot swaps.
An "R" indicates post-rebuilding -- this assumes that there is enough time
between failures to rebuild a hot-swappable spare.
-- Donnie Berkholz