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]
>>>
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>> --
>> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> --
>> Author: claudio cutelli
>> INET: [EMAIL PROTECTED]
>>
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>
>
> --
> 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
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>
// George Schlossnagle
// Principal Consultant
// OmniTI, Inc http://www.omniti.com
// (c) 301.343.6422 (e) [EMAIL PROTECTED]
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