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Setting mincache=direct and convosync=direct for VxFS on Solaris 10

lingzong
Not applicable
Hi,

I am helping a Solaris+VxFS customer to use directio for an application that does not use O_SYNC. The customer reported that only setting convosync=direct does not have much performance benifits, but by adding mincache=direct there is a significant performance gain. 

By definitions:
"mincache=direct will cause any reads without the O_SYNC flag, or any writes without the O_SYNC flag, VX_DSYNC, VX_DIRECT, and VX_UNBUFFERED caching advisories, to be handled as if the VX_DIRECT caching advisory had been set."

and

"convosync=direct will cause any reads or writes with the O_SYNC flag to be handled as if the VX_DIRECT caching advisory had been set. "

This application doesn't use read/write() with O_SYNC.

My question is:

Is "convosync=direct" mandatory for VxFS using directio?
  or
Can we use "mincache=direct" only for VxFS directio? And why?
 
Thanks in advance for any explanation.
1 ACCEPTED SOLUTION

Accepted Solutions

Bala_Kumaresan
Level 2
Employee
if application doesn't use read/write with O_SYNC, mincache=direct will convert the application i/o to direct i/o. convosync=direct will not have any effect for this application, which is not issuing O_SYNC write.

Bala

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2 REPLIES 2

Bala_Kumaresan
Level 2
Employee
if application doesn't use read/write with O_SYNC, mincache=direct will convert the application i/o to direct i/o. convosync=direct will not have any effect for this application, which is not issuing O_SYNC write.

Bala

sunshine_2
Level 4


please refer to this doc..

http://support.veritas.com/docs/285316