A number of amusing aspects to this discussion. - I've carried out similar tests using the Intel X-25M with both PG and DB2 (both on linux). While it is a simple matter to build parallel databases on DB2, on HDD and SSD, with buffers and tablespaces and logging and on and on set to recreate as many scenarios as one wishes using a single engine instance, not so for PG. While PG is the "best" OS database, from a tuning and admin point of view there's rather a long way to go. No one should think that retail SSD should be used to support an enterprise database. People have gotten lulled into thinking otherwise as a result of the blurring of the two use cases in the HDD world where the difference is generally just QA.
- All flash SSD munge the byte stream, some (SandForce controlled in particular) more than others. Industrial strength flash SSD can have 64 internal channels, written in parallel; they don't run on commodity controllers. Treating SSD as just a faster HDD is a trip on the road to perdition. Industrial strength (DRAM) SSDs have been used by serious database folks for a couple of decades, but not the storefront semi-professionals who pervade the web start up world. - The value of SSD in the database world is not as A Faster HDD(tm). Never was, despite the naive' who assert otherwise. The value of SSD is to enable BCNF datastores. Period. If you're not going to do that, don't bother. Silicon storage will never reach equivalent volumetric density, ever. SSD will never be useful in the byte bloat world of xml and other flat file datastores (resident in databases or not). Industrial strength SSD will always be more expensive/GB, and likely by a lot. (Re)factoring to high normalization strips out an order of magnitude of byte bloat, increases native data integrity by as much, reduces much of the redundant code, and puts the ACID where it belongs. All good things, but not effortless. You're arguing about the wrong problem. Sufficiently bulletproof flash SSD exist and have for years, but their names are not well known (no one on this thread has named any), but neither the Intel parts nor any of their retail cousins have any place in the mix except development machines. Real SSD have MTBFs measured in decades; OEMs have qualified such parts, but you won't find them on the shelf at Best Buy. You need to concentrate on understanding what can be done with such drives that can't be done with vanilla HDD that cost 1/50 the dollars. Just being faster won't be the answer. Removing the difference between sequential file processing and true random access is what makes SSD worth the bother; makes true relational datastores second nature rather than rocket science. Robert -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
