fsadm -e and -d

[Rita C Workman]

I have never run this for defrag'ing disks and extents. From what I understand this should not impact Oracle (although obviously I plan to run it with Oracle db's down..).
I have both 10.2 and 11.0 systems with various instances of Oracle and other software. K boxes mostly. Most boxes sharing an EMC disk array. Most filesystems running about 8gb.

My question is: Does anyone do this regularly? Can you give me any 'how long it generally takes'? Any cautions or 'watch out for(s)?

Thanks,

[James R. Ferguson · Accepted solution]

Rita:

My experience with this one is somewhat limited. The few times I have done it takes "quite a while" [a non-ORACLE filesystem of about 15GB took a couple of hours on a K370]. Run times are more certainly dependent on the extent of fragmentation. I would certainly do it during off-hours. I would also run the preview" variants (-D and -E) first to see if you think you will really gain much. Hope this helps.

...JRF...

[Cheryl Griffin]

Defrag time depends on the extent of fragmentation and the size of the filesystem.

-E to determine if the fragmentation impairs performance
-e is for regaining performance

-D to determine if directory fragmentation impairs performance
-d is for regaining performance

So, I would use -D and -E first to see if it would be advantageous to run -d -e.

[Duncan Edmonstone]

Rita, what's in your Oracle file systems?

If it's mostly oracle data files then there's not much point in running the fsadm -ed more than once as the meta data for the filesystem remains pretty much unchanged (a small number of large files)

If it's archived redo though, it's definately worth defragging occasionally as a large number of relatively small files will be created regularly in the FS leading to more fragmentation. However given the sensitvity of the archived redo, I would only do this with the database down and after you have backed up the file system.

I'm afraid I don't do this often enough to remember how long it takes. I do seem to remember that you need at least 2% free space for it to work though.

[John Palmer]

Rita,

If your filesystems contain only a few large Oracle data files then you are unlikely to gain much as they are won't to be fragmented.

Best gains are on volatile systems with lots of small files which are constantly being created and deleted.

Regards,
John

[Rita C Workman]

Thank you all for your input...based on what I am reading, there is little to be gained in performance since what you describe is primarily what exists. With very few exceptions....and those weren't the ones I planned to defrag anyway.

Thanks ... at least it's one less thing to have to schedule for !

[Dave Wherry]

I'll add one comment/experience.
I defrag'd several smaller file systems on my development box. Did it on-line and everything was fine. Little impact, of course it is a lightly loaded system.
Did it to one of my oracle file systems on my production box. The fs is 14GB of various table spaces. Took a huge performance hit. SAP processes were queuing up and not getting serviced. Users calling all over the place.
If you determine it will be valuable to you, do it with your database down or at least during off hours.