Re: Defragfs gotchas?
- From: "Davignon, Edward" <Edward.Davignon@xxxxxxxxxxxxxx>
- Date: Tue, 8 May 2007 11:27:50 -0400
I just checked one of our AIX 5.1 ML8 systems using instfix -ia and
searched the output for defragfs.
Before running defragfs on AIX 5.1, I would run the following commands
to make sure the following APARs are installed:
instfix -ik IY38698
instfix -ik IY28806
instfix -ik IY50790
instfix -ik IY52025
instfix -ik IY62599
instfix -ik IY66450
instfix -ik IY76827
Are you using jfs or jfs2 for the /var file system? (command: lsfs /var)
I didn't check fix central, are there any other APARs that pertain to
AIX 5.1 and defragfs that are not listed above?
Here is the list of APAR abstracts and symptom texts from instfix -ia
========================================================================
======
IY38698 Abstract: defragfs upates timestamps of files on JFS2
IY38698 Symptom Text:
Timestamp on files gets updated when defragfs command is run
on a J2 filesystem.
This does not happen on JFS filesystem.
========================================================================
======
IY28806 Abstract: System assert following defragfs call using 64-bit
kernel
IY28806 Symptom Text:
System assert following defragfs call under 64-bit kernel.
========================================================================
======
IY50790 Abstract: data corruption after defragfs run
IY50790 Symptom Text:
Some files may be corrupted after running defragfs.
This only happens on JFS2
========================================================================
======
IY52025 Abstract: malloc failed error due to signed int overflow
IY52025 Symptom Text:
Running defragfs will result in the following message:
error: defragfs 0506-403 malloc failed
========================================================================
======
IY62599 Abstract: defragfs failed on very fragmented file system
IY62599 Symptom Text:
defragfs failed
========================================================================
======
IY66450 Abstract: defragfs could corrupt JFS2 and may lead to crash
IY66450 Symptom Text:
Running defragfs command on a JFS2 filesystem could lead
to system crash and filesystem corruption.
========================================================================
======
IY76827 Abstract: Data corruption on JFS after running defragfs
IY76827 Symptom Text:
Data loss can result from the use of the JFS defragfs
utility on a large-file enabled filesystem. Corruption may
appear in filesystem metadata or file data and may occur
significantly after defragfs has run. The use of defragfs
should be avoided until after this APAR is applied.
This problem may also result in a crash in v_findiblk,
dlistadd, or other JFS metadata corruption related
crashes. In these cases, user data may be written over
filesystem metadata.
If defragfs has been run recently on a large-file enabled JFS
filesystem, fsck should be run to repair any filesystem
metadata issues. In addition, any data verification services
available should be run for the data on those filesystems
(e.g. database verification services).
========================================================================
======
Edward.Davignon@xxxxxxxxxxxxxx
Lead Analyst - Distributed Systems
Utility Shared Services - IT
Energy East Corporation
Office Phone: (585) 771-4952
"Measure twice. Cut once."
-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@xxxxxxxxxxxxx] On Behalf Of
Karl Jones
Sent: Tuesday, May 08, 2007 10:29 AM
To: aix-l@xxxxxxxxxxxxx
Subject: Defragfs gotchas?
Last night I got an error indicating that we should run defragfs on /var
on our 5.1 system.
Any concerns about doing this? Do I need to wait until after hours to
do this?
Here's the output of a dry run:
F50:# defragfs -r /var
statistics before running defragfs:
number of free fragments 90159
number of allocated fragments 171985
number of free spaces shorter than a block 208
number of free fragments in short free spaces 876
statistics after running defragfs:
number of free spaces shorter than a block 30
number of free fragments in short free spaces 146
other statistics:
number of fragments moved 5896
number of logical blocks moved 806
number of allocation attempts 541
number of exact matches 245
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