Sync redo log waits
- From: Saad Khan <saad4u@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 19 Feb 2013 12:06:24 -0500
Hi Gurus,
I'm writing regarding our prod environment with Oracle 11g (11.2.0.2) on
64-bit AIX 6.1 with storage on IBM XIV devices.
The users have been complaining a very poor performance and all sorts of
delays.
The issue I've been seeing very large waits for "Average Time to Sync a
Redo Log". Its reaching as high as 600 ms. Right now we've four redo
groups ( 2 members each) with a size of 600 MB each.
Now when I checked the hourly logswitch frequency sometimes the count is
upto 18 per hour (very alarming) while sometimes its just 1 or 2 as given
below. Should I increase the size of redologs? What else can I do to curb
these waits? The related parameters configured are :
log_checkpoint_timeout = 1800
fast_start_mttr_target = 0
log_checkpoint_internal = 0
Appreciate earliest help. Here is the hourly logswitch count:
HOURLY LOGSWITCH FREQUENCY:
=====================
DAY HOUR TOTAL
--------------- ---- -----
2013-02-17 22 4
2013-02-17 23 4
2013-02-18 00 13
2013-02-18 01 5
2013-02-18 02 3
2013-02-18 03 1
2013-02-18 04 6
2013-02-18 05 5
2013-02-18 06 3
2013-02-18 07 3
2013-02-18 08 2
DAY HOUR TOTAL
--------------- ---- -----
2013-02-18 09 1
2013-02-18 10 1
2013-02-18 11 2
2013-02-18 12 1
2013-02-18 13 3
2013-02-18 14 4
2013-02-18 15 4
2013-02-18 17 1
2013-02-18 18 2
2013-02-18 22 4
2013-02-18 23 4
DAY HOUR TOTAL
--------------- ---- -----
2013-02-19 00 12
2013-02-19 01 1
2013-02-19 02 2
2013-02-19 03 1
2013-02-19 04 5
2013-02-19 05 3
2013-02-19 06 2
2013-02-19 07 1
2013-02-19 08 1
*2013-02-19 09 18*
*2013-02-19 10 18*
DAY HOUR TOTAL
--------------- ---- -----
2013-02-19 11 4
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