Re: Enterprise Manager warns of blocking on LGWR
From: Mladen Gogala <gogala.mladen_at_gmail.com>
Date: Thu, 7 Dec 2017 21:52:58 -0500
Message-ID: <cac1ca64-4716-41d9-088c-15bb202d513c_at_gmail.com>
Date: Thu, 7 Dec 2017 21:52:58 -0500
Message-ID: <cac1ca64-4716-41d9-088c-15bb202d513c_at_gmail.com>
On 12/07/2017 04:18 PM, Mark W. Farnham wrote:
>
> There are a few avenues of research to discover why LGWR might be
> identified as blocking.
>
By far the most frequent cause of the problems with LGWR are too small
log files. I have once seen a customer which had 3 checkpoints per
minute. Of course, redo log files were 50M in size. Furthermore,
duplexing redo logs is completely unnecessary. Duplexing is done by the
storage (RAID 1+0 or some other form of RAID) and it is unnecessary to
waste the expensive server CPU and IO capacity to do the job that
storage does anyway.
Also, it would help to know which exact event are the processes blocked by LGWR waiting on.
Regards
-- Mladen Gogala Oracle DBA http://mgogala.freehostia.com -- http://www.freelists.org/webpage/oracle-lReceived on Fri Dec 08 2017 - 03:52:58 CET