topic Re: Indexed File Fragmentation in Operating System - OpenVMS

Indexed File Fragmentation

Jack Trachtman — Wed, 22 Mar 2006 16:32:14 GMT

How is the internal fragmentation of an indexed file determined? Does ANALYZE/RMS provide this information? If so, what fields should I look at and what are the "rules of thumb" to determine a "degree of fragmentation" to help determine when to reorganize the file?

PS Since ANA/RMS doesn't work on an OPEN file, is there another program which will work with open files?

TIA

Re: Indexed File Fragmentation

Arch_Muthiah — Wed, 22 Mar 2006 17:32:07 GMT

Jack,

There is Dynamic Load Balancer Plus (DLB Plus) is Automatic OpenVMS Tuning and I/O Analysis Tool. There is a utility comes with this, called RSFRAG, under
12.3 RSFRAG - File Fragmentation Analysis, can be used for your needs...

http://www.ttinet.com/doc/dlbplus_clean.html#preface

Archunan

Re: Indexed File Fragmentation

Arch_Muthiah — Wed, 22 Mar 2006 17:45:44 GMT

Jack,

There are other couple other Fragmentation analysis tools available....

DFU is avaailable on the OpenVMS Freeware CD.

and FRAGMENT also in the freeware CD, you can download from here...
http://vms.tuwien.ac.at/freeware/FRAGMENT/

Archunan

Re: Indexed File Fragmentation

Arch_Muthiah — Wed, 22 Mar 2006 17:47:41 GMT

Jack,

And from google, I found these for you...

Compaq's DSNLINK tool and one more third party tools Diskeeper 7.2, the details abt these tools are...
http://www.diskeepereurope.com/en/02_sb/xhtml/openvms.htm

archunan

Re: Indexed File Fragmentation

Phil.Howell — Wed, 22 Mar 2006 18:11:53 GMT

To look at internal rms bucket/key info you need the freeware tool rms_tune_check.
The definitive guide to all this is
http://h71000.www7.hp.com/openvms/journal/v2/articles/rms.html
Phil

Re: Indexed File Fragmentation

Hein van den Heuvel — Wed, 22 Mar 2006 21:25:40 GMT

Archunan,
Sorry, but I fail to see how any of the 3 replies addreses the specific question being raised.

Phil,
Ayup, my tune_check tool will report excessive RRV's
But the article highlights just the potential Duplicate Key problem which tune_check may discover.
I intend to do a 'deleted key chain' article for the June 2006 edition.

The tool is in:
http://h71000.www7.hp.com/freeware/freeware60/rms_tools/
I'll attach a minor update which I'll submit with other tools fro the next Freeware release.

Jack,
It is good to see you are aware of the potential of 'internal fragmenation'.
ANAL/RMS only provides this data in an indirect way.
There are tools made just for this, but I couldn't find a public pointer just now (I have my copies ;-).
Tune_check -s=-1 will do an exhausitve count of rrv's

Unlike anal/rms my tune_check will work on open files, and does not lock. Of course this means it potentially could get confused, for a life file, but i have yet to see that happen, and if it does... just run again.
An other silly, but sometimes appropriate, alternative is to use backup/ignore=interlock and analyze the copy.
The best solution really is to analyze the old file from before the last convert.

Anyway.. don't get too excited about internal fragmenation. Yes it is not clean and yes it may cause additional IOs, but for most appliactions I have dealt with there are much bigger problems to attack first
(global buffers? bucket size? locking?).

Come to the OpenVMS Bootcamp in May 2006 here in Nashua and I'lll tell you all about it, or feel free contact me ofline for individual help/consultancy.

Hope this helps,
Hein.

Re: Indexed File Fragmentation

Robert Atkinson — Thu, 23 Mar 2006 04:46:27 GMT

Jack, another tool no body has mentioned is ANAL/RMS/FDL :-

"For indexed files, the FDL file contains special analysis sections you can use with the EDIT/FDL Optimize script to make better design decisions when you reorganize the file."

You could potentially use the data in the optimise file to determine how much space is taken up with empty buckets, and if the file needs converting.

Rob.

Re: Indexed File Fragmentation

Jack Trachtman — Mon, 27 Mar 2006 18:13:59 GMT

Thanks all