Re: JFS2 - Part Deux

I've only heard one vendor note to the contrary. They asked to not use
inline logs because they preferred to have the log on a separate physical
device. Essentially their preferred scheme was:

hdisk1: FS1jfs2, FS2jfs2log
hdisk2: FS2jfs2, FS1jfs2log

So, I don't think there are any true performance reasons to not go inline
in the age of the SAN, but, you may be forced to manage logs on some servers.

John T. Mills

-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@xxxxxxxxxxxxx] On Behalf Of
Sandor W. Sklar
Sent: Wednesday, January 31, 2007 2:29 PM
To: aix-l@xxxxxxxxxxxxx
Subject: Re: JFS2 - Part Deux

Just to add to the mix, I agree totally. These days, the only "physical
disks" I have on my systems are the two mirrored rootvg disks; all of the
other disks are redundant fibre-attached storage provided by a mix of FC and
ATA disks in EMC storage arrays, carved into different RAID sets, and
fronted by a bunch of memory cache in the array.

The concept of "physical spindle location" is meaningless in such an
environment, I think.

-s-

On Jan 31, 2007, at 11:44 AM, Enrique Sanchez Vela wrote:

Jeff,

I would agree with you but now hdisks, or should I say "Physical
Volumes from AIX prespective", are more loosely related to physical
disks than ever. so having the inline log in the same physical volume
would be spread across multiple physical hard drives and might not
impact as much.

I believe that inline log would give you an advantage over the more
traditional jfs2log on a recovery situation where you need to run a
fsck on multiple large filesystems sharing the same jfs2log (if they
are sharing the log).

I am not sure about this, since AIX might perform a serialized fsck as
it finds the filesystems in /etc/filesystems whether you use inline,
multiple jfs2log or not.

I have not run any tests.

regards,
enrique.





--- Jeff Barratt-McCartney <jbarratt@xxxxxxxxxxx>
wrote:


i dont normally use inline logs, as they dont afford you the
opportunity to modify disk placement of logs for performance

-----Original Message-----
From: IBM AIX Discussion List on behalf of Mark Schlechte
Sent: Wed 1/31/2007 9:44 AM
To: aix-l@xxxxxxxxxxxxx
Subject: JFS2 - Part Deux


With the discussion about jfs2 I decided it was a
good time to post my question about Inline logs and
jfs2.
We still run 4.3.3 systems but I do have a couple of
5.2 servers so when I have the opportunity I've done
a little bit of work with JFS2.
When I created some file systems recently I went
with jfs2 and chose inline log, mostly because I
didn't have a separate disk to use for that purpose.
Good? Bad? Depends on the workload characteristics?


I noticed Ku had mentioned Inline worked for him.


mark




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