Re: High DASD utilization

["Al Barsa, Jr." <barsa2@xxxxxxx>]

At 08:44 PM 7/8/98 -0500, you wrote:

I might add that new system values were added in V4R2 to deal with the
running out of disk space problem.

Name:               QSTGLOWLMT                                       V4 R2.0 

Description:        Auxiliary Storage Lower Limit

IBM Initial Value:   5.0000 (percent of system ASP storage)

Length & Type:      Decimal:     6.4

Comments:           This is the percentage of remaining auxiliary storage
for the system ASP, at which point the action specified by the system value
QSTGLOWACN will be invoked.  This is the percentage of unused storage.
(i.e.: for QSTGLOWACN to be invoked for the shipped default, the percentage
of storage utilization would have to be 95.0000%).

Change will take effect immediately.

User must have *ALLOBJ and *SECADM authority to change this system value. 
 


Name:               QSTGLOWACN                                       V4 R2.0 

Description:        Auxiliary Storage Lower Limit Action

IBM Initial Value:  '*MSG'

Length & Type:      Character:  10


Valid Values and their Meanings:

'*MSG'         Send message CPI099C to QSYSMSG and QSYSOPR.  This message
is also send for all other actions.

'*CRITMSG'     Send critical message CPI099B to the user defined in service
attributes to receive critical messages.

'*REGFAC'      Submit a job to call exit programs registered for the
QIBM_QWC_QSTGLOWACN.

'*ENDSYS'      End the system to a restricted state.

'*PWRDWNSYS'   Execute PWRDWNSYS OPTION(*IMMED) RESTART(*YES).

Comments:           Change will take effect immediately.

User must have *ALLOBJ and *SECADM authority to change this system value. 

Hope this helps.

Al



>At 09:27 AM 7/7/98 -0700, Ken Graap wrote:
>>Several years ago I had a conversation with IBM about the long term
>>affect of running at 95% plus AUX Storage utilization on an AS/400. I
>>can't remember the conversation exactly, but I do seem to remember that
>>there are some dire consequences of having auxiliary storage remain very
>>high for extended periods of time.
>>
>>The part I seem to have retained in my brain was that eventually the
>>system would have to be completely restored.... Yikes!
>>
>>Does anyone have any knowledge of what the consequences are of running
>>between 95-99% AUX Storage utilization for months on end might be?
>
>Ken,
>
>AFAIK, this is still true. When you exceed about 70%, you start to pay a
performance penalty, because the system must put more effort into finding
places to stuff new data. During normal operation however, the system must
use some DASD for work areas, paging, etc. This space gradually grows over
time. When you approach 100%, you risk having the system require more space
for internal use when none is available. If this happens, the system will
crash, and you will be forced to IPL. The (exteeeeended) IPL process will
recover the used work space, and all will be relatively well. If however,
you start writing records or creating objects and actually use up all of
the available disk storage, and the system has not accumulated a sufficient
amount of recoverable space, you may not even be able to IPL. If this
happens, you will need to scratch and restore everything. Depending on the
amount of DASD on your system, 95%, while not good, may or may not actually
be dangerous. I would hit !
>!
>the 
>big red flapper switch before I reached 99% though. Those 96 hour days are
not a lot of fun.
>
>Pete
>
>
>Pete Hall
>peteh@inwave.com 
>http://www.inwave.com/~peteh/
>
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Al Barsa, Jr. - Account for Midrange-L
Barsa Consulting, LLC.  
400 > 390

Phone:  914-251-9400
Fax:    914-251-9406





Private mail should be sent to barsa@ibm.net
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