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Home -> Community -> Mailing Lists -> Oracle-L -> RE: File open event
Hi Arun,
Did you check whether LGWR and CKPT are the main culprits?
Yes, I have seen lots of 'file open' waits on a Solaris system running Cached Quick I/O, but they had lots of web servers making frequent short connections to the database, so I did not associate it with QIO. Interesting hypothesis however.
@ Regards, @ Steve Adams @ http://www.ixora.com.au/ @ http://www.christianity.net.au/
-----Original Message-----
Sent: Wednesday, 16 May 2001 22:31
To: Multiple recipients of list ORACLE-L
Thanks for the reply Steve,
this event was not proping up before until we enabled QUICK I/O and that too
after we enabled Cached Quick I/o.
one more thing I wanted to know have you faced any issues are come across,
When you have enabled QUICK I/O on Sun Solaris it causes causes too much
wait I/O,due to this you will see Db sequential read and buffer busy wait.On
one of our busiest days it came to an extent where the cpu idle time came to
0%.
The only option was to enable Cached Quick I/o which is now causing the
reverse, it causing write complete waits and this file open event,which was
worrying me.
Please let me know if you faced any issue.
>From: "Steve Adams" <steve.adams_at_ixora.com.au>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: File open event
>Date: Tue, 15 May 2001 00:10:42 -0800
>
>Hi Arun,
>
>Foreground processes open the datafiles only when they need to read from
>them
>(or write to them in the case of a sort). The 'file open' wait event
>represents
>the opening of and typically the first I/O operation against that datafile,
>however, sometimes a few extraneous I/O operations against other datafiles
>seem
>to be included. The 'truss' output below shows a 'file open' wait delimited
>by
>calls to the 'times()' system call, with two extraneous reads included in
>the
>wait. Incidentally, it also shows how Oracle duplicates the file descriptor
>onto
>a high numbered file descriptor.
>
> times(0xEFFF8F78) = 31885993
> open64("/database/PRODidxC01.dbf", O_RDWR|O_DSYNC) = 11
> getrlimit(RLIMIT_NOFILE, 0xEFFF5100) = 0
> fstat64(403, 0xEFFF5068) = 0
> fstat64(402, 0xEFFF5068) Err#9 EBADF
> fcntl(11, F_DUP2FD, 0x00000192) = 402
> close(11) = 0
> fcntl(402, F_SETFD, 0x00000001) = 0
> ioctl(402, 0x0403, 0xEFFF50C4) = 0
> pread64(402, "0602\0\0\081 /A5 . -1A8C".., 8192, 0x25F4A000) = 8192
> pread64(405, "0602\0\00380 <01 /BC *18".., 8192, 0x07802000) = 8192
> pread64(408, "0602\0\00E81 B18 0848AF6".., 8192, 0x28430000) = 8192
> times(0xEFFF7D00) = 31885997
>
>Large numbers of 'file open' waits are seen in applications that frequently
>disconnect from the instance and then reconnect later, rather than leaving
>their
>connection open. Also, if the instance has been up for a long time, the
>CKPT
>process can accumulate a lot of 'file open' waits - several per file per
>checkpoint.
>
>In your case the number of 'file identify' waits makes me suspect the
>second
>explanation. In general the file identify operation is just done once per
>datafile and controlfile. It validates the filename and establishes a 'file
>information block' in the SGA that is then shared by all processes needing
>to
>open any of the datafiles or controlfiles. On the other hand, LGWR
>identifies
>each member of the selected logfile group as part of each logfile switch.
>So a
>large number of 'file identify' waits is consistent with the instance
>having
>been up for a long time with regular log switches.
>
>Your average time waited for these waits is acceptable. In general, the
>average
>'file open' time should be of the same order of magnitude as the average
>'db
>file sequential read' time. If not, you should ensure that none of the
>Oracle
>files have what the operating system regards as "long" filenames, or a
>parent
>directory with a "long" filename. See "What's in a name?" at
>http://www.ixora.com.au/newsletter/2000_12.htm#file_names in last
>December's
>issue of Ixora News on that. In some cases, it also helps to hold the log
>files
>open. See "Holding the log files open" at
>http://www.ixora.com.au/tips/tuning/log_switch.htm on that.
>
>@ Regards,
>@ Steve Adams
>@ http://www.ixora.com.au/
>@ http://www.christianity.net.au/
>
>
>-----Original Message-----
>Sent: Saturday, 12 May 2001 0:26
>To: Multiple recipients of list ORACLE-L
>
>
>Can somebody please explain to me what this event is, I am not able to find
>good documentation on this issue.
>
>EVENT TOTAL_WAIT TOTAL_TIME TIME_WAITE AVERAGE_WA
>-------------- ---------- ---------- ---------- ----------
>file identify 38343 0 3135 .08176199
>file open 9436698 0 3934742 .416961738
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Steve Adams
> INET: steve.adams_at_ixora.com.au
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: ARUN K C INET: arun_k_c_at_hotmail.com 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: ListGuru_at_fatcity.com (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: Steve Adams INET: steve.adams_at_ixora.com.au 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: ListGuru_at_fatcity.com (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).Received on Wed May 16 2001 - 08:23:31 CDT
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