http://www.dba.5341.com/
http://www.dba.5341.com/
Edwin,
You can only simulate asynchronous I/O as per the note. This is not the
same as having kernel level asynchronous I/O, as there will be overheads.
Even so, the available throughput may be
sufficient for your requirement. I suggest you try it and see.
From:
oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of edwin devadanam
Sent: 06 August 2007 16:01
To: rxsherm@interealm.com;
knecht.stefan@gmail.com; ax.mount@gmail.com;
Cc: oracle-l@freelists.org
Subject: Re: Async_io set up HP-UX
for 10g Instances(these are apps instances)
Hi All,
Please add
This is production database:
SQL> show sga
Total System Global Area 3215950016 bytes
Fixed
Size
741568 bytes
Variable Size
1056964608 bytes
Database Buffers 2147483648
bytes
Redo
Buffers
10760192 bytes
1) As discussed we can't use disk_asynch_io=true in HP-UX(its using jfs not raw
filesystem)
2) Is HP-UX(JFS) doesnt suport asynchronous io?(operating system level)
3) dbwr_io_slaves=x or db_writer_processes=y which one does asynchronous
i/o?(refer Note:47328.1)
4)Keeping db_writer_processes=y only will i not achieve asynchornous i/o?
Thanks In Advance,
Edwin.K
Roby
>
> - disk_asynch_io is used to enable the oracle kernel to make use of
> asynchronous io, IF the OS supports it.
And you really DO want to figure out if your OS supports it.
Otherwise if you turn it on and its not supported, your database is
essentially making two I/O calls for every one... One to aio_write
(which fails) and then an immediate call to pwrite after. I can't
tell you how many environments I come into where disk_asynch_io is
set to true and it isn't supported.
--Roby
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