On Wed, Apr 7, 2010 at 3:27 PM, Vick Khera <vivek@xxxxxxxxx> wrote: > On Fri, Mar 26, 2010 at 3:50 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: >> here is a _used_ 320gb ramsan for 15k :-). dram storage is pricey. >> > > I think using DRAM as the base is way better than flash. Just use the > flash or a regular disk as the backup with a battery to power the > backup operation. > > I have in my storage room a DRAM based SCSI storage device made by > Imperial Technology. It was totally the bees knees in 2000 when I > bought it (with 1GB of RAM) for almost $30k. Upgraded a year later to > 5Gb for another $15k. It has 4 low-profile/offset SCSI-2 connectors > and full battery backed up UPS internal to it, and writes itself to a > traditional disk drive on power outage, and continually ran self > diagnostics to ensure that everything was just right. > > Free. But it doesn't power up. Probably needs a cap replaced or > something simple like that. dram storage makes sense in some cases but is generally so expensive that it throws off the whole hardware cost/engineering calculus even with the insane expense of writing software (even to the 0.0001% of it managers that understand this). that's saying something. the idea behind flash storage though was to provide at least decent performance at a reasonable cost. making dram storage fault tolerant takes a lot of engineering thus the high cost. as a dba, the idea of flash being able to be swapped in for sata spinning drives for a 10-20x gain in iops makes me vibrate. except that the fault tolerance issue isn't worked out yet. so I continue to buy bulk fossilized dinosaur plop and waste precious time figuring out how to make it work with otherwise fairly modern equipment. did i mention that i was annoyed with intel? check out their faq entry on ssd/write back cache: Does the Intel SSD have a write cache? Yes. However data caching is limited to the controller for enhanced performance. huh!? merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
