When I run
SELECT DB_EXTENDED_PROPERTY('IOParallelism','SYSTEM');on my PC (1 processor 16 cores, RAID 1 HHDs) I get a value of 64. On a client's server (2 processors, 48 cores, v fancy EMC all SSD SAN, connected by fiber channel) I get a value of 1. This latter doesn't change if
ALTER DATABASE CALIBRATE PARALLEL READ;is run.
Is this expected and does it matter?
This is a busy server with around 900 concurrent users, so I wouldn't be expecting a lot of hugely parallel query plans to be being chosen, but will other things be effected? I can't find a lot in the docs about IOParallelism beyond "Returns the estimated number of simultaneous I/O operations supported by the dbspace." One would think that a high number would be good - reducing queueing, but I suspect it's not that simple.
asked 28 Jul '15, 09:11