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Does addition of disk require running AUTOGEN

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Chaim Budnick
Regular Advisor

Does addition of disk require running AUTOGEN

At one of our customer sites a new DKA device was added.

Does this in itself require/justify/indicate that AUTOGEN be run?

Chaim
9 REPLIES
Kris Clippeleyr
Honored Contributor
Solution

Re: Does addition of disk require running AUTOGEN

Chaim,

No need to run AUTOGEN when a disk is added.

Greetz,

Kris.
I'm gonna hit the highway like a battering ram on a silver-black phantom bike...
Himanshu_3
Valued Contributor

Re: Does addition of disk require running AUTOGEN

Hi Chaim,

Although autogen is not required to be run after a new device is added but possibly its always better to do following if you are on a cluster and want your systems to identify the new device which has been added

$ MC SYSMAN
SYSMAN> SET ENVIRONMENT/CLUSTER
SYSMAN> IO AUTOCONFIGURE/LOG
SYSMAN> EXIT


If you are haveing Fibre channel you can also put following to assign names
SYSMAN> IO FIND_WWID


Cheers,
HP
Bojan Nemec
Honored Contributor

Re: Does addition of disk require running AUTOGEN

Chaim,

The number of disks partecipate in the computation of the NPAGEDYN parameter. So autogen is needed only if you are low on nonpaged dynamic memory.

Bojan
Uwe Zessin
Honored Contributor

Re: Does addition of disk require running AUTOGEN

"SYSMAN> IO FIND_WWID" is required to make the necessary entries to SYS$DEVICES.DAT for fibre channel attached tape devices and their robotics. For disk devices an "IO AUTOCONFIGURE" is sufficient.
.
John Gillings
Honored Contributor

Re: Does addition of disk require running AUTOGEN

AUTOGEN counts the number of disks and uses the value in calculating appropriate settings for several parameters, including NPAGEDYN, PAGEDYN and sizing the ACP cache.

Unless your system is running very tight on resources, adding a single disk probably won't make much difference, so you can most likely avoid the inconvenience of a reboot.

Running AUTOGEN is no big deal - you don't have to reboot and use the recommendations (indeed, I would always recommend AGAINST letting AUTOGEN reboot your system). To see how much difference it would make, run AUTOGEN to SETPARAMS:

$ @SYS$UPDATE:AUTOGEN SAVPARAMS SETPARAMS

and compare the new values with the old:

$ DIFF/PARA SYS$SYSTEM:SETPARAMS.DAT

if you don't like the new values, modify MODPARAMS.DAT to adjust them back to what you want. Make sure you don't leave the system in a state that running AUTOGEN causes surprises!
A crucible of informative mistakes
Jan van den Ende
Honored Contributor

Re: Does addition of disk require running AUTOGEN

Chaim,

John's is a wise advise!

We take it even one step further:
Each week at a (expected) rather quiet time, we run a batch which essentially does:
$ @AUTOGEN SAVPARAMS TESTFILE
This does all calculations and reporting, without making any modification.
So, we read the reports, and decide if any action is needed.
And because of the regular weekly reports, we also notice any CHANGES in the reports.
THOSE are the ones that best indicate any slipping away from optimal settings, allowing to foresee deviations growing to unacceptable level, and that gives us time for preemptive corrective actions, at a time that suits us.

HTH

Cheers.

Have one on me.

Jan
Don't rust yours pelled jacker to fine doll missed aches.
Wim Van den Wyngaert
Honored Contributor

Re: Does addition of disk require running AUTOGEN

I would add that each modification reported by autogen must be investigated. A looping program can generate too many processes, too many network connections etc and autogen would increase the parameters based upon this erronious loop.

Wim
Wim
Keith Parris
Trusted Contributor

Re: Does addition of disk require running AUTOGEN

> Each week at a (expected) rather quiet
> time, we run a batch which essentially
> does:
> $ @AUTOGEN SAVPARAMS TESTFILE

I'd recommend doing the feedback data data collection:
$ @AUTOGEN SAVPARAMS
during a busy (peak) time if possible. Some of the feedback data AUTOGEN gathers doesn't have peak value data cells available, and only snapshot "in-use" values can be gathered, so it seems to me that the results could be slightly better if one gathers feedback at a peak time.

The remainder of the AUTOGEN calculations can be deferred to a less-busy time:
$ @AUTOGEN GETDATA TESTFILES
Jan van den Ende
Honored Contributor

Re: Does addition of disk require running AUTOGEN

Thanks for the hint Keith!

I'll make the advised change.
Always prepared to leave a good thing for a better one!

Cheers.

Have one on me.

Jan
Don't rust yours pelled jacker to fine doll missed aches.