"Dawid Kuroczko" <qnex42@xxxxxxxxx> writes: > It is also possible to present block devices from NetApp over iSCSI or FC > (I am not sure about licensing model though). You get all the goodies > like thin provisioning (only non-zero blocks are allocated), snapshots and > all, but you see it as a block device. Works fine. Note that Postgres doesn't expect to get "out of space" errors on writes specifically because it pre-allocates blocks. So this "thin provisioning" thing sounds kind of dangerous. > It is also worth to mention that NetApp utilizes somewhat "copy on write" > write strategy -- so whenever you modify a block, new version of the block > is written on its WAFL filesystem. In practical terms it is quite resilient to > random writes (and that read performance is not stellar ;)). Again, Postgres goes to some effort to keep its reads sequential. So this sounds like it destroys that feature. Random writes don't matter so much because Postgres has its WAL which it writes sequentially. Writes to data files aren't in the critical path and can finish after the transaction is committed. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Get trained by Bruce Momjian - ask me about EnterpriseDB's PostgreSQL training! -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
