On Fri, Nov 13, 2009 at 9:48 AM, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: > I think RAID6 is gonna reduce the throughput due to overhead to > something far less than what a software RAID-10 would achieve. I was wondering about this. I think raid 5/6 might be a better fit for SSD than traditional drives arrays. Here's my thinking: *) flash SSD reads are cheaper than writes. With 6 or more drives, less total data has to be written in Raid 5 than Raid 10. The main component of raid 5 performance penalty is that for each written block, it has to be read first than written...incurring rotational latency, etc. SSD does not have this problem. *) flash is much more expensive in terms of storage/$. *) flash (at least the intel stuff) is so fast relative to what we are used to, that the point of using flash in raid is more for fault tolerance than performance enhancement. I don't have data to support this, but I suspect that even with relatively small amount of the slower MLC drives in raid, postgres will become cpu bound for most applications. merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
