Redundancy and power
Monday, May 03, 2010
11:31 AM
Redundancy and power
Flash drives are much less reliable than disk. 
But they take a lot less idle power.
Optimal writes for flash reuse each block the same number of times. 
But optimal writes for disk are not so constrained
Disk accesses tend to be local
So we can cache disk accesses in flash! 
Hybrid strategy: use flash drive as a cache for hard disk, spin down disk until needed. 
Less "reliable" (MTBF) but power savings of up to 30%. 
In clouds, point reliability doesn't matter!