On Fri, Apr 4, 2014 at 11:15 AM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: > On Fri, Apr 4, 2014 at 11:04 AM, Steve Crawford > <scrawford@xxxxxxxxxxxxxxxxxxxx> wrote: >> On 04/03/2014 12:44 PM, Brent Wood wrote: >> 2. Do I need both BBU on the RAID *and* capacitor on the SSD or just on one? >> Which one? I'm suspecting capacitor on the SSD and write-through on the >> RAID. > > You need both. The capacitor protects the drive, the BBU protects the > raid controller. You don't technically need the BBU / flashback memory IF the controller is in write through. My experience has been that the BBU helps a lot on write heavy applications or to get maximum performance for your money. On most cards, it's < $100 so unless you can definitively show no real performance loss without one, get one. OTOH it's worth testing to be sure. But the BBU does a lot to reorder writes and such and flattens out bursty write performance very well. It also speeds up checkpointing if / when it has to occur. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
