set dsync and directio options according to device type
Dears, what does mean the 'unknown device type' in description column in the result of sp_helpdevice ?
And for these devices, is it preferred to set dsync option to true and directio to false.
Are those two options (dsync and directio) affect on transaction log devices which are file system devices??
And for these devices, is it preferred to set dsync option to true and directio to false.
Are those two options (dsync and directio) affect on transaction log devices which are file system devices??
ASKER
Dear Joe,
kindly note the attached file, on the same location I stored log device (in its description: file system device), and data device (in its description: unknown device type).
Thank you.
sp_helpdevice-result.png
kindly note the attached file, on the same location I stored log device (in its description: file system device), and data device (in its description: unknown device type).
Thank you.
sp_helpdevice-result.png
ASKER CERTIFIED SOLUTION
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ASKER
Dear Joe,
No problem, Thank you very much
No problem, Thank you very much
Generally it is better to have directio true and dsync false if you have an OS and file system type that supports directio.
If you are using any kind of file system devices, we want at least one of those options to be true (exception - devices used for tempdb where we want both to be false). directio is better performance than dsync.
If you use raw partitions the options are ignored, effectively all raw partition i/o is directio anyway.