RE: LGWR blocking sessions
Date: Thu, 11 Jun 2009 15:51:51 -0700
OEM should provide more information, are they log buffer waits, log file synch, etc. Where are the online redologs located? Are these waits actually causing any problems? How long does the blocking last? How many sessions are queued?
SLAC National Accelerator Center
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Joel.Patterson_at_crowley.com Sent: Thursday, June 11, 2009 12:41 PM
Subject: LGWR blocking sessions
My log writer is triggering an alert from OEM that it is blocking sessions. (SID ### is blocking -- which is LGWR).
I have googled, and searched metalink, and come across log file sync's, and even Kevin Closson's interesting blog about io and cpu (again :)).
Even though I can find people (several) with the same issue and question, I did not come up with any solutions that where directed specifically.
10.2.0.4, peoplesoft, SAN. Sidenote. Archiver is copying logfiles to a Quantum dxi7500, (with compression and deduping software bundled).
Any ideas where to go from here? (I'll be back early tomorrow)
Alert log snippet during time receiving two such alerts which looks normal. No trace files. Some db's have been know to warn of the 500ms write threshold was exceeded, but not here now.
Thu Jun 11 11:04:57 2009
Beginning log switch checkpoint up to RBA [0x1bc1.2.10], SCN: 2847388841 Thu Jun 11 11:04:57 2009
Thread 1 advanced to log sequence 7105 (LGWR switch) Current log# 1 seq# 7105 mem# 0: /u02/oradata/HRPROD/log01a.log Current log# 1 seq# 7105 mem# 1: /u03/oradata/HRPROD/log01b.log Thu Jun 11 11:10:02 2009
Completed checkpoint up to RBA [0x1bc1.2.10], SCN: 2847388841 Thu Jun 11 12:11:53 2009
Beginning log switch checkpoint up to RBA [0x1bc2.2.10], SCN: 2847490018 Thu Jun 11 12:11:53 2009
Thread 1 advanced to log sequence 7106 (LGWR switch) Current log# 2 seq# 7106 mem# 0: /u02/oradata/HRPROD/log02a.log Current log# 2 seq# 7106 mem# 1: /u03/oradata/HRPROD/l0g02b.log Thu Jun 11 12:17:11 2009
Completed checkpoint up to RBA [0x1bc2.2.10], SCN: 2847490018 Thu Jun 11 13:07:20 2009
Beginning log switch checkpoint up to RBA [0x1bc3.2.10], SCN: 2847597436 Thu Jun 11 13:07:20 2009
Thread 1 advanced to log sequence 7107 (LGWR switch) Current log# 3 seq# 7107 mem# 0: /u02/oradata/HRPROD/log03a.log Current log# 3 seq# 7107 mem# 1: /u03/oradata/HRPROD/log03b.log Thu Jun 11 13:12:36 2009
Completed checkpoint up to RBA [0x1bc3.2.10], SCN: 2847597436
http://www.freelists.org/webpage/oracle-l Received on Thu Jun 11 2009 - 17:51:51 CDT