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тАО01-17-2007 04:18 AM
тАО01-17-2007 04:18 AM
how to check if process uses async io?
i want to make sure, that my oracle instance uses async io. i guess, there should be aio_xxx syscalls visible in glance/truss for process?
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тАО01-17-2007 04:30 AM
тАО01-17-2007 04:30 AM
Re: how to check if process uses async io?
Async IO is NOT supported on file systems, only on raw devices and particular volume managers like Veritas.
http://download-uk.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams061.htm#sthref246
Rgds...Geoff
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тАО01-17-2007 05:28 PM
тАО01-17-2007 05:28 PM
Re: how to check if process uses async io?
You can use these commands to check if there is any activity on async driver.
# fuser /dev/async
# lsof -p
Hope this help,
Tom
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тАО01-17-2007 06:47 PM
тАО01-17-2007 06:47 PM
Re: how to check if process uses async io?
2tom quach: on one server i see oracle processes, interacting with /dev/async, but there is no `asyncdisk' driver in kernel (according to sam. it shows OUT in all positions for this driver). imho, async io isn't used.
btw, oracle recommeds to create /dev/async with 0x000007 minor number. and i have 0x000000 minors on all servers. is it worth to recreate /dev/async with mentioned minor number?
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тАО01-17-2007 07:23 PM
тАО01-17-2007 07:23 PM
Re: how to check if process uses async io?
as mentioned in the metalink note 401323.1, the minor number can be one of the following values:
0x000000 default-immediate reporting will not be used and a cache flush will be done before posting an IO operation complete
0x000001 enable immediate reporting
0x000002 flush the CPU cache after reads
0x000004 allow disks to timeout
0x000005 is a combination of 1 and 4
0x000007 is a combination of 1, 2 and 4
it is up to you to decide and check the reason for the value being 0x000000 on the other servers.
But I would prefer to use the Oracle recommended value: 0x000007
good luck!
kind regards
yogeeraj
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тАО01-18-2007 12:31 AM
тАО01-18-2007 12:31 AM
Re: how to check if process uses async io?
Rgds...Geoff
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тАО01-18-2007 01:28 AM
тАО01-18-2007 01:28 AM
Re: how to check if process uses async io?
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1081006
Rgds...Geoff
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тАО01-31-2007 06:51 PM
тАО01-31-2007 06:51 PM
Re: how to check if process uses async io?
we've got 'direct path read' and 'direct path write' events in oracle's v$* views after turning async io on.
that DB is using raw devices which are under LVM management.
also oracle document A97297_01 telling, that oracle 9i _IS_ using async io and all of features of HP asyncdsk driver.