On 09/01/2011 11:14 PM, Jesper Krogh wrote:
It is "really expensive" to go over 512GB memory and the performance regression for just hitting disk in a system where you assume everything is in memory is really huge. SSD makes the "edge" be a bit smoother than rotating drives do.
Ironically, this is actually the topic of my presentation at Postgres Open. We transitioned to NVRAM PCI cards for exactly this reason. Having a giant database in cache is great, until a few reads come from your slow backing disks, or heaven-forbid, you have to restart your database during a high transactional period.
Lemme tell ya... no RAID-10 in the world can supply 12k TPS with little to no warning. A good set of SSDs or PCI cards can.
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