Re: Informal poll: What's your avg redo write time?

From: Jeremy Schneider <jeremy.schneider_at_ardentperf.com>
Date: Thu, 19 Feb 2015 16:29:10 -0500
Message-ID: <CA+fnDAaFZGOdyTQCAJYa82r7tXdZGpRNkFZ-QuBCRa5ocOJ8Dw_at_mail.gmail.com>

if you're troubleshooting a LGWR issue, you might see if this script gives you some additional useful info - it helped me a bunch with some LGWR related troubleshooting last year.

https://github.com/fidelinho/SAP_Note_1438410_V49/blob/master/SystemStatistics_LGWR.txt

i haven't looked at kyle's script to see what exactly it's doing - but assuming it's just showing the time for write calls to the storage, then my take would be that <1ms shouldn't be problematic on a typical system. timings are going to depend greatly on what sort of storage people are on. what kind of storage are you on?

-J

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On Thu, Feb 19, 2015 at 4:10 PM, Rich Jesse
<rjoralist3_at_society.servebeer.com> wrote:


> Hey all,

>

> In 11.2.0.3 on AIX 7.1, I'm tracing down an issue on an SR and stumbled into

> the world of LGWR.  It's causing blocking locks (falsely being reported, I

> believe) when stressed, so I'm looking at LGWR performance.

>

> Using Kyle Hailey's average log write time query at the bottom of -- NOTE:

> TUNING PACK LICENSE REQUIRED --

> http://www.oaktable.net/content/lgwr-redo-write-times-log-file-parallel-write

> my average is about 0.52ms with 90% of all between 0.4ms and 0.6ms, and

> another 8.4% at 0.7ms.

>

> Knowing that there's over-committing going on, I'm thinking that 0.52ms

> isn't my issue, but what are other folks getting?

>

> TIA!

> Rich

>

> p.s.  Testing HTML formatting -- apologies if this message doesn't look like

> it should!

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Received on Thu Feb 19 2015 - 22:29:10 CET