George,
Those writes are unbuffered (so synchronous) and each thread will write them
out and will wait for the write to finish and then update the AIO control
block in the parent thread to indicate that the I/O took place. The parent
thread will check this control block to make sure that the I/O really
happened. If there is an error or some time out experid and the i/o didn't
complete, the parent thread will assume an error.
Anjo.
George Schlossnagle wrote:
> On Monday, April 15, 2002, at 02:08 PM, Anjo Kolk wrote:
>
> > Claudio,
> >
> > All writes in Oracle are synchronous, they are just fired
> > asynchronously. So
> > even the DBWR writes synchronously.
>
> My dbw uses asynchronous writes.... I'm writing to qio files, which
> means that they bypass buffer cache, but I think it's misleading to call
> those 'synchronous writes', they're asynchronous, unbuffered writes.
>
> 14:28:09(george@core-0)[~]> truss -tkaio -twrite -tread -p `ps -ef |
> grep dbw | grep -v grep | awk '{print $2}'`
> kaio(AIOWRITE, 396, 0xB0258000, 8192, 0x4FBF6000, 0x01974EC8) = 0
> kaio(AIOWRITE, 308, 0xB6BFE000, 8192, 0x48478000, 0x01B20518) = 0
> kaio(AIOWRITE, 396, 0xB921A000, 8192, 0x249E8000, 0x019C5558) = 0
> kaio(AIOWRITE, 396, 0xB4584000, 8192, 0x24F7E000, 0x0196CA84) = 0
> kaio(AIOWRITE, 396, 0xB82BC000, 8192, 0x6D822000, 0x01B543CC) = 0
> kaio(AIOWRITE, 313, 0xB5ED4000, 8192, 0x1FCD2000, 0x019EE1D8) = 0
> kaio(AIOWRITE, 395, 0xBF256000, 8192, 0x21AE6000, 0x01971958) = 0
> kaio(AIOWRITE, 313, 0xB1700000, 8192, 0x1FCD4000, 0x019B65D0) = 0
> kaio(AIOWRITE, 396, 0xBA238000, 8192, 0x24F86000, 0x01B5E32C) = 0
> ....
>
> > So individual writes are synchronously, they are just fired off
> > asynchronously.
> >
> > Anjo Kolk.
> >
> > claudio cutelli wrote:
> >
> >> Hi,
> >> which background process had the problem?
> >> because if lgwr, it already write in sync mode ...
> >>
> >> ----- Original Message -----
> >> To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]>
> >> Sent: Monday, April 15, 2002 5:33 PM
> >>
> >>> We have implemented a Sun Solaris Cluster (4 machines), connected
> >>> to
> >>> an EMC storage array. The migration began last fall, and we now have
> >>> 15
> >>> Oracle instances, with a mixture of 8.1.6 and 8.1.7, located there.
> >>> We
> >>> recently have had 2 occurances of asynchronous I/O wait times
> >>> exceeded.
> >>> When this occurs, every database crashes at the same time. The
> >>> solution
> >>> from EMC is to turn asynchronous I/O off in all of the Oracle
> >>> instances
> >>> (disk_async_io = false) and to increase the database writer slaves
> >>> (dbwr_io_slaves = <something not 0>) to emulate asynchronous I/O.
> >>> Has anyone run into this problem before? If so, how did you
> >>> "correct" it? My feeling is that EMC is trying to give us a bandage
> >>> to
> >>> cover up the real problem, by trying to get Oracle to ignore it.
> >>>
> >>> Thank you.
> >>>
> >>> --
> >>> Scott Canaan ([EMAIL PROTECTED])
> >>> (585) 475-7886
> >>> "Life is like a sewer, what you get out of it depends on what you put
> >>> into it" - Tom Lehrer
> >>>
> >>>
> >>> --
> >>> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> >>> --
> >>> Author: Scott Canaan
> >>> INET: [EMAIL PROTECTED]
> >>>
> >>> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> >>> San Diego, California -- Public Internet access / Mailing Lists
> >>> --------------------------------------------------------------------
> >>> To REMOVE yourself from this mailing list, send an E-Mail message
> >>> to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
> >>> the message BODY, include a line containing: UNSUB ORACLE-L
> >>> (or the name of mailing list you want to be removed from). You may
> >>> also send the HELP command for other information (like subscribing).
> >>>
> >> --
> >> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> >> --
> >> Author: claudio cutelli
> >> INET: [EMAIL PROTECTED]
> >>
> >> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> >> San Diego, California -- Public Internet access / Mailing Lists
> >> --------------------------------------------------------------------
> >> To REMOVE yourself from this mailing list, send an E-Mail message
> >> to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
> >> the message BODY, include a line containing: UNSUB ORACLE-L
> >> (or the name of mailing list you want to be removed from). You may
> >> also send the HELP command for other information (like subscribing).
> >
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Anjo Kolk
> > INET: [EMAIL PROTECTED]
> >
> > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> > San Diego, California -- Public Internet access / Mailing Lists
> > --------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
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> > (or the name of mailing list you want to be removed from). You may
> > also send the HELP command for other information (like subscribing).
> >
> >
> // George Schlossnagle
> // Principal Consultant
> // OmniTI, Inc http://www.omniti.com
> // (c) 301.343.6422 (e) [EMAIL PROTECTED]
> // 1024D/1100A5A0 1370 F70A 9365 96C9 2F5E 56C2 B2B9 262F 1100 A5A0
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: George Schlossnagle
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
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> also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Anjo Kolk
INET: [EMAIL PROTECTED]
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
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