SQLIO Parameters
i’m looking info how sqlio parameters should set simulate sql server behavior possible:
1. the <number of threads (per test file)> in datafile setup. according documentation should set equal number of cpu’s. told sql server use 1 io tread per datafile accesses. should value remain 1?
2. –o parameter (the number of outstanding i/o > requests). should put here value of disk queue length available in perfmon?
thanks
geert vanhove
1. the <number of threads (per test file)> in datafile setup. according documentation should set equal number of cpu’s. told sql server use 1 io tread per datafile accesses. should value remain 1?
not sure info came from, sql server i/o asynchronous , use available worker in pool. start using 1 thread per distinct disk when first create database , files created/initialized first time that's all. it's resource availability dependent after that, no 1-1 mapping or that.
if only used 1 thread per file, huge bottleneck modern storage devices can handle massive iops. serialized making i/o response time unacceptable.
2. –o parameter (the number of outstanding i/o > requests). should put here value of disk queue length available in perfmon?
suggest start 8 , move until see throughput drop. goal figure out disk's actual capacity. looking @ perfmon's dql doesn't paint accurate picture since sqlio test , workload perfmon observed not identical.
check out http://technet.microsoft.com/en-us/library/cc966412.aspx#edaa for sqlio specific guidance , when done, read rest of whitepaper if haven't done so. 1 of best writings available on sql server , io (right alongside sql server io basics 1 & 2)
no great genius has ever existed without touch of madness. - aristotle
SQL Server > SQL Server Database Engine
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