Re: Sizing JFSLog
From: Bill Thompson (bill.thompson_at_GOODYEAR.COM)
Date: 06/27/03
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Date: Fri, 27 Jun 2003 07:01:09 -0400 To: aix-l@Princeton.EDU
Theresa,
One more word on this: You originally asked where you could find
documentation on this and I don't believe that was answered. There are two
very good Redbooks on the AIX logical volume manager:
AIX Logical Volume Manager from A to Z: Introduction and Concepts
http://www.redbooks.ibm.com/redbooks/pdfs/sg245432.pdf
AIX Logical Volume Manager from A to Z: Troubleshooting and Commands
http://www.redbooks.ibm.com/redbooks/pdfs/sg245433.pdf
The following excerpt comes from the Redbook "AIX Logical Volume Manager
from A to Z: Introduction and Concepts":
5.2.7.9 Journaled file system log size issues
Another size-related issue is the size of the JFS log. In most instances,
multiple journaled file systems use a common log configured to be one
physical partition in size. For example, after initial installation, all
file systems
within the root volume group use logical volume hd8 as a common JFS log.
When file systems exceed 2 GB or when the total amount of file system space
using a single log exceeds 2 GB, the default log size may not be
sufficient. In
either case, the log sizes should be scaled upward as the file system size
increases. The JFS log is limited to a maximum size of 256 MB. A rule of
thumb is 2 MB log for 4 GB of journaled file system. This does not mean
that
you need a 50 MB log logical volume if you have 100 GB of file systems in a
particular volume group. It also depends on the amount of write activity
performed. If you have 100 GB of file systems, and the applications do not
write huge amounts of data, you will not need a big log logical volume.
HTH
Bill Thompson
Sr UNIX Systems Administrator
The Goodyear Tire & Rubber Co.
Contains Confidential and/or Proprietary Information
May Not Be Copied or Disseminated Without Express Consent of The Goodyear
Tire & Rubber Company.
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----- Original Message -----
From: "Theresa Sarver" <tsarver.IFMC@SDPS.ORG>
Newsgroups: bit.listserv.aix-l
To: <aix-l@Princeton.EDU>
Sent: Thursday, June 26, 2003 4:10 PM
Subject: Re: Sizing JFSLog
> Thank you all for your feedback - I guess I wasn't aware that there
wasn't a "hard-fast rule" for this paramete? Anyway all the responses have
been most helpful.
>
> So thank you again;
> Theresa
>
> >>> aixgeek@YAHOO.COM 06/26/03 02:15PM >>>
> Bah.
>
> If you have a massive amount of file system meta
> changes, than 2MB for 1GB is a good idea, but that
> assumes METADATA changes (i.e., massive file creations
> and deletions).
>
> If this is a database server (create file once and
> then never change its STRUCTURE), then you can get by
> with a minimally-sized log device (one logical
> partition) for your entire volume group.
>
>
> --- Bob.Kelley@BRINKSINC.COM wrote:
> > yes......a good rule of thumb is 2MB per 1G
> >
> > .....you should also include performance
> > considerations when designing your
> > logs, ie striping the logs for improved IO
> > performance
> >
> > Bobby Kelley
> > Sr. AIX/UNIX Administrator
> >
> >
> >
> >
> > |---------+---------------------------->
> > | | Theresa Sarver |
> > | | <tsarver.IFMC@SDP|
> > | | S.ORG> |
> > | | Sent by: IBM AIX |
> > | | Discussion List |
> > | | <aix-l@Princeton.|
> > | | EDU> |
> > | | |
> > | | |
> > | | 06/26/2003 11:22 |
> > | | AM |
> > | | Please respond to|
> > | | IBM AIX |
> > | | Discussion List |
> > | | |
> > |---------+---------------------------->
> >
> >
> >
------------------------------------------------------------------------------------------------------------------------------|
> > |
> >
> > |
> > | To: aix-l@Princeton.EDU
> >
> > |
> > | cc:
> >
> > |
> > | Subject: Sizing JFSLog
> >
> > |
> >
> >
> >
------------------------------------------------------------------------------------------------------------------------------|
> >
> >
> >
> >
> > Hi All;
> >
> > What is the proper size of the JFSLog on an AIX
> > system (either 433 or 5L)?
> >
> > I have always set it at the default of 1PP.
> > However, I have a colleague
> > that is saying that "IBM recommends a 2 MB log size
> > per 1 GB of file system
> > space."
> >
> > I can't find any documentation stating that either
> > one is correct...does
> > anyone know where I might find some?
> >
> > Thank you!
> > Theresa
> >
> > NOTICE TO BRINK'S EMPLOYEES:
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>
>
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