Disk Fragmentation

[Aaron Lewis_1]

We have a pair of EVA3000's. I am trying to determine how much file fragmentation for several hundred RMS files, across about a dozen DGA devices. I have DFU, but that only displays 'most fragmented'. I know I can do image copies to correct the fragmentation, but this will require downtime. I want to be able to fix 'the worst' volumes first, and schedule the others to be done at more convient times.

[Kris Clippeleyr]

Aaron,
I suggest you install DFG, or another good disk defragger. DFG not only can show you the fragmentation but does a good job in mending it.
Regards,
Kris (aka Qkcl)

[Peter Weaver_1 · Accepted solution]

DFU SEARCH disk/FRAGMENT=MINIMUM=2 will show you all the files on the disk with 2 or more fragments.

DFU DEFRAG filename will defrag a file, but does nothing to defragment your free space so files will contiguous but you may not have enough contiguous free space left to create new files or expand a .DIR.

A .COM like;

$!
$ assign no dfu$nosmg
$ dfu search 'p1/frag=min=2-
/format="$dfu defrag !AS" /out=sys$scratch:xdefrag_temp.com
$ @sys$scratch:xdefrag_temp
$!

will do a defrag on every fragmented file, but as I mentioned above, that might not be such a good idea.

[Robert Atkinson]

You could download Raxco's Perfectdisk, and use the analysis tools in it. I think it'll work without a licence (but don't vouch for the legality of doing that!)

Rob.

[Ian Miller.]

You can use the report part of DFO without a licence
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=979158

Is the fragmentation causing you a problem?

[Jeroen Hartgers_3]

Nevr use raxco perfect or ultra disk on vms if you have a version of vms high then 7.2 because this software will corrupt your files.

The freeware DFU gives you a good indication of you disk situation. It is also possible to defrag (closed) files with dfu.

[Robert Atkinson]

Jereon - as we have been doing since March, please can you clarify what the problem is.

I'd hate to have a potential time-bomb sat there.

Robert.

[Simon Setina]

Raxco PerfectDisk works fine on OpenVMS higer than 7.2, but does not support multipathing

[Robert Gezelter]

Aaron,

Just a small note about the free space issue.

If your defragment utility does not defragment free space, you can obviously get the equivalent by creating a file (on a running system production system I would counsel no more than 50% of the "working float" space required), And letting the utility de-fragment it. (Of course, you then delete this file, which will leave a large block of contiguous space in its place).

- Bob Gezelter, http://www.rlgsc.com

[Jan van den Ende]

Aaron,

it is not a TOTAL replacement of defragging, but VMS (actually: RMS) can do VERY well in diminishing the ill effects of fragmentation.

Set your SYSGEN param ACP_WINDOW to max (255), and ALL accessed file headers are loaded COMPLETELY in memory.
At the cost of some (not even that much!) extra memory allocation, you get rid of all window turns. You are still left with SOME extra IOs in accessing very fragmented files, but in general RMS is quite good at concealing the ill effects, if you just let it do its work!

hth,

Proost.

Hace one on me.

jpe

[Aaron Lewis_1]

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