I'm wondering what the write penalty is for RAID 3?
I know for 5 it is 4, and 6 is 6, but I'm not entirely sure how it would work for RAID3.
The thing that confuses me a little with raid 3 is the fact that any request requires all the blocks in a strip to be read:
from wiki: This happens because any single block of data will, by definition, be spread across all members of the set and will reside in the same location. So, any I/O operation requires activity on every disk and usually requires synchronized spindles.
This implies to me that 1 write IOP for one a block (or byte) update would require the following:
- Read all blocks in stripe.
- Update stripe where necessary and calculate parity.
- Rewrite all blocks to disk.
My query is how many RW does 1 and 3 count for (disk number dependent of course)?