ASG
IBM
Zystems
Cressida
Icon
Netflexity
 
  MQSeries.net
Search  Search       Tech Exchange      Education      Certifications      Library      Info Center      SupportPacs      LinkedIn  Search  Search                                                                   FAQ  FAQ   Usergroups  Usergroups
 
Register  ::  Log in Log in to check your private messages
 
RSS Feed - WebSphere MQ Support RSS Feed - Message Broker Support

MQSeries.net Forum Index » IBM MQ Installation/Configuration Support » qm.ini Log stanza

Post new topic  Reply to topic
 qm.ini Log stanza « View previous topic :: View next topic » 
Author Message
yiftah_o
PostPosted: Wed Jul 24, 2002 6:32 am    Post subject: qm.ini Log stanza Reply with quote

Newbie

Joined: 30 Jun 2002
Posts: 9
Location: Raanana, Israel

Hi

in the qm.ini file there is a parameter:
LogWriteIntegrity=TripleWrite

I would like to understand what does this parameter control and what are the available options for it (beside TripleWrite).

thanks
Yiftah[/code][/quote]
Back to top
View user's profile Send private message
bower5932
PostPosted: Wed Jul 24, 2002 8:20 am    Post subject: Reply with quote

Jedi Knight

Joined: 27 Aug 2001
Posts: 3023
Location: Dallas, TX, USA

There is some information in the System Admin manual on this:

LogWriteIntegrity=SingleWrite|DoubleWrite|TripleWrite
The LogWrite attribute specifies the method the logger uses to reliably write log records.
SingleWrite Where a non-volatile write cache is used (for example, ssa write cache enabled) then it is safe for the logger to write log records in a single write.
DoubleWrite In some cases an additional write is necessary to write log records with more integrity.
TripleWrite In some cases another additional write is necessary to write log records with complete integrity, but at the cost of performance. This is the default value.
Back to top
View user's profile Send private message Send e-mail Visit poster's website AIM Address Yahoo Messenger
yiftah_o
PostPosted: Wed Jul 24, 2002 8:32 am    Post subject: Reply with quote

Newbie

Joined: 30 Jun 2002
Posts: 9
Location: Raanana, Israel

how can I determine the level of integrity suitable for me?
in what cases can persistent information be lost when using LogWriteIntegrity=SingleWrite ?
Back to top
View user's profile Send private message
RogerLacroix
PostPosted: Wed Jul 24, 2002 7:53 pm    Post subject: Reply with quote

Jedi Knight

Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada

It goes something like this:

If you have a queue manger failure and when you tell your manager:
    (1) s/he says "Who cares" then use single write.
    (2) s/he paces in and out of your office while you recover the queue manager's data then use double write.
    (3) s/he has security in your office with packing boxes then use triple write.

Hope that helps.

later
Roger...
Back to top
View user's profile Send private message Visit poster's website
yiftah_o
PostPosted: Thu Jul 25, 2002 1:17 am    Post subject: Reply with quote

Newbie

Joined: 30 Jun 2002
Posts: 9
Location: Raanana, Israel

what if my manager has security in my office with packing boxes in case performance goes down?
will it help to decrease the LogWriteIntegrity or should I pack my bags ?
Back to top
View user's profile Send private message
mrlinux
PostPosted: Thu Jul 25, 2002 5:09 am    Post subject: Reply with quote

Grand Master

Joined: 14 Feb 2002
Posts: 1261
Location: Detroit,MI USA

Well to determine the level of integrity you need,

1) How often do your systems lose power and go down ?? if more than once a year and the possible loss of messages is not easily recoverable then go for triple.
2) How often does the box crash for software reasons ??? see above
3) How hard is it to determine/recreate the data lost when the system
comes down. If you have some kind of resend process then you
can reduce the logwrites to single.


This is only my opinion !!!!!
_________________
Jeff

IBM Certified Developer MQSeries
IBM Certified Specialist MQSeries
IBM Certified Solutions Expert MQSeries
Back to top
View user's profile Send private message Send e-mail
yiftah_o
PostPosted: Thu Jul 25, 2002 5:16 am    Post subject: Reply with quote

Newbie

Joined: 30 Jun 2002
Posts: 9
Location: Raanana, Israel

thanks a lot guys

Yiftah
Back to top
View user's profile Send private message
Michael Dag
PostPosted: Mon Feb 16, 2004 10:14 am    Post subject: Reply with quote

Jedi Knight

Joined: 13 Jun 2002
Posts: 2607
Location: The Netherlands (Amsterdam)

Just dug up this interesting post as I am playing around with

Single/Double/Triple write logging to see the difference in persistent performance. (and there IS! )

from a 'safety' point of view (in relation to to Single/Double/Triple write) is there difference between LINEAR and CIRCULAR logging?

i.e. if using LINEAR logging SingleWrite is 'as safe as the bank'
i.e. if using CIRCULAR logging SingleWrite is NOT 'as safe as the bank'
as CIRCULAR logs need verification if the data is really delivered, before the logspace can be released/overwritten
(which does not occur when using LINEAR logging), hence the need for TripleWrite.

Michael
Back to top
View user's profile Send private message Visit poster's website MSN Messenger
Display posts from previous:   
Post new topic  Reply to topic Page 1 of 1

MQSeries.net Forum Index » IBM MQ Installation/Configuration Support » qm.ini Log stanza
Jump to:  



You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Protected by Anti-Spam ACP
 
 


Theme by Dustin Baccetti
Powered by phpBB © 2001, 2002 phpBB Group

Copyright © MQSeries.net. All rights reserved.