compact zparm

Philippe Godfrin

compact zparm
Greetings listees,

Happy New Year to all...

Does anyone use COMPACT=YES for archiving to tape?

pg

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Cathy Taddei

Re: compact zparm
(in response to Philippe Godfrin)
Yes.

-----Original Message-----
From: DB2 Data Base Discussion List [mailto:[login to unmask email]On
Behalf Of Philippe Godfrin
Sent: Monday, January 05, 2004 7:26 AM
To: [login to unmask email]
Subject: compact zparm


Greetings listees,

Happy New Year to all...

Does anyone use COMPACT=YES for archiving to tape?

pg

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Avram Friedman

Re: compact zparm
(in response to Cathy Taddei)
We used COMPACT for our archives at a previous shop

Be sure to pay serious attention in the installation guide about NEVER using these tapes for backout. One can do backout with these tapes but it is very very very slow as the logs can not be decompressed when read backwards. If you can't afford a multi day outage when you say have a run away job that needs to go to archive for the backout I would think twice before enabling this option.

Philippe Godfrin wrote:

> Greetings listees,
>
> Happy New Year to all...
>
> Does anyone use COMPACT=YES for archiving to tape?
>
> pg
>
> ---------------------------------------------------------------------------------
> Welcome to the IDUG DB2-L list. To unsubscribe, go to the archives and home page at http://www.idugdb2-l.org/archives/db2-l.html. From that page select "Join or Leave the list". If you will be out of the office, send the SET DB2-L NO MAIL command to [login to unmask email] The IDUG List Admins can be reached at [login to unmask email] Find out the latest on IDUG conferences at http://conferences.idug.org/index.cfm

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Charles Crockett

Re: compact zparm
(in response to Avram Friedman)
It was my vague recollection that some of the newer tape technologies always compact, or perhaps had an option that your MVS installers could set that would compact everything, so this may be a mute point now.

Charlie Crockett
Former DB2 Sys Prog (anyone know of any openings?)

Philippe Godfrin <[login to unmask email]> wrote:
Does anyone use COMPACT=YES for archiving to tape?


Charles Crockett
Phoenix, Arizona, USA
[login to unmask email]
602-997-8643 (home) 602-803-0379 (cel)
602-224-6928 (office) 602-955-9262 (fax)

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Cathy Taddei

Re: compact zparm
(in response to Charles Crockett)
I'm not sure I'm interpreting the manual perfectly, but I don't think
COMPACT is obsolete on newer tape drives. This is from the install guide:

"This option only applies to data written to a 3480 device that has the
improved data recording capability (IDRC) feature. When this feature is
turned on, hardware in the tape control unit writes data at a much higher
density than normal, allowing for more data on a volume. Specify NO if you
do not use a 3480 device with the IDRC feature or a 3490 base model, with
the exception of the 3490E. Specify YES if you want the data to be
compacted.

"If you use compression or auto-blocking on the tape unit, you will need to
ensure that you do not read backwards on the tape unit...."

The way I read it,
1) You have to have newer technology that has IDRC built in or added on.
Rather than making COMPACT obsolete, the newer tech makes it possible.
2) I interpret "compression or auto-blocking on the tape unit" to be
external to DB2, at the device or operating system level, and if you use
this _in addition to_ COMPACT=YES, then read backwards is not a good thing.
I may be wrong on this, but fortunately for us, all of our batch
applications do commits at controllable intervals. The manual strongly
suggests you have enough log space on DASD to contain your largest possible
unit of work.

Regards,
Cathy Taddei

-----Original Message-----
From: DB2 Data Base Discussion List [mailto:[login to unmask email]On Behalf Of
Charles Crockett
Sent: Monday, January 05, 2004 11:50 AM
To: [login to unmask email]
Subject: Re: compact zparm


It was my vague recollection that some of the newer tape technologies always
compact, or perhaps had an option that your MVS installers could set that
would compact everything, so this may be a mute point now.

Charlie Crockett
Former DB2 Sys Prog (anyone know of any openings?)

Philippe Godfrin <[login to unmask email]> wrote:

Does anyone use COMPACT=YES for archiving to tape?




Charles Crockett
Phoenix, Arizona, USA
[login to unmask email]
602-997-8643 (home) 602-803-0379 (cel)
602-224-6928 (office) 602-955-9262 (fax)

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Philippe Godfrin

Re: compact zparm
(in response to Cathy Taddei)
Howdy folks,

I read the same entries in the docs and I did not get a warm fuzzy feeling.
Being relatively conservative with backup and recovery, I tend towards a
previous note recommending caution when using this option - I agree.

I've always preferred using DFSMS conmtrolled disk for archiving anyway -
it's fast, reliable and permits parallel recovery.

Any other thoughts?

pg

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