On 15/03/13 07:54, Bruce Momjian wrote:
Only use SSDs with a BBU cache, and don't set SSD caches to write-through because an SSD needs to cache the write to avoid wearing out the chips early, see: http://momjian.us/main/blogs/pgblog/2012.html#August_3_2012
I not convinced about the need for BBU with SSD - you *can* use them without one, just need to make sure about suitable longevity and also the presence of (proven) power off protection (as discussed previously). It is worth noting that using unproven or SSD known to be lacking power off protection with a BBU will *not* save you from massive corruption (or device failure) upon unexpected power loss.
Also, in terms of performance, the faster PCIe SSD do about as well by themselves as connected to a RAID card with BBU. In fact they will do better in some cases (the faster SSD can get close to the max IOPS many RAID cards can handle...so more than a couple of 'em plugged into one card will be throttled by its limitations).
Cheers Mark -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
