On 08/12/2010 17:13, Amaral, Rui wrote:
Why in theory? Please have a look at a snapshot of statistics from one node of our data warehouse cluster running on EMC DMX4 storage:Yes in theory that can be true but it depends on several factors:
*AVG_WRITE_TIME* *TOTAL_WRITES* *AVG_READ_TIME* *TOTAL_READS* 1.1 40460 26.78 35864Much better write times than read times (the high read time is also contributed from the large IO the database tends to do).
Why do you think write back cache should be disabled? Proper storage systems have sufficient battery backups built in to flush the whole cache to disk in case of power failure.1) assuming write-back caches on the array have not been disabled (which in my opinion they should be)
Harel Safra