ADSM-L

Re: Is reclamation working?

2002-09-11 12:22:37
Subject: Re: Is reclamation working?
From: Todd Lundstedt <Todd_Lundstedt AT VIA-CHRISTI DOT ORG>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 11 Sep 2002 11:08:11 -0500
I have seen the number of reclaimable tapes grow steadily over the course
of a week, but the percent utilized average would go down over time.
If I remember correctly, reclaiming tapes in offsite pools is similar to a
migration, in that the reclamation process moves the data in the largest
"chunks" possible.
For example...
Day one, you have 3 tapes that need to be reclaimed in the offsite pool,
but by the end of the day, they each only get down to 25-30% utilized.
Day two, three more tapes are added to the reclamation list, but since
onsite tapes mounted for reclamation will have more data to be moved on
them for the newly added tapes, the tapes from day one will not get
reclaimed as much as the tapes from day two.  So now you end up with the
day one tapes an additional 5% less utilized, and the day two tapes 20%
less utilized.
Day three comes along, adding four tapes that are 50% utilized, and the
list of tapes grows, but the reclaimable percentage, on average, is still
less.  Each day, this happens without fully reclaiming some tapes.

What I do when I see this condition is set the reclamation threshold
higher.. say 95% or 90%.. and get the tapes that are 5 or 10% utilized
fully reclaimed.  Later, I will set the threshold lower, in increments that
make sense (say, only two or four tapes will match the reclamation
threshold) so that tapes get fully reclaimed.

The situation you are seeing can happen very easily if your primary storage
pool is collocated, but your copy storage pool is not.  Lots of primary
storage pool tape mounts will slow down your reclamation process.

Hope this helps
Todd



|--------+-------------------------->
|        |          "Gill, Geoffrey |
|        |          L."             |
|        |          <GEOFFREY.L.GILL|
|        |          @SAIC.COM>      |
|        |          Sent by: "ADSM: |
|        |          Dist Stor       |
|        |          Manager"        |
|        |          <[email protected]|
|        |          T.EDU>          |
|        |                          |
|        |                          |
|        |          09/11/02 10:05  |
|        |          AM              |
|        |          Please respond  |
|        |          to "ADSM: Dist  |
|        |          Stor Manager"   |
|        |                          |
|--------+-------------------------->
  
>---------------------------------------------------------------------------------------------------------------------|
  |                                                                             
                                        |
  |      To:     ADSM-L AT VM.MARIST DOT EDU                                    
                                               |
  |      cc:                                                                    
                                        |
  |      Fax to:                                                                
                                        |
  |      Subject:     Is reclamation working?                                   
                                        |
  
>---------------------------------------------------------------------------------------------------------------------|




TSM Server is AIX 4.3.3 running TSM 4.2.1.9

I have noticed I have about 145 volumes that are less than 25% utilized,
most of these are in the offsite pool. Reclamation runs on the offsite pool
daily, sometimes, like this morning, I find it is still running.
Reclamation
kicks off at 5PM with reclaim=50. I'm not understanding why these aren't
being reclaimed quicker.

Just a few:
U00582                    OFFSITE_POOL   3590CLASS    25,415.9    0.0
Full
U00586                    OFFSITE_POOL   3590CLASS    19,665.6    0.0
Full
U01638                    OFFSITE_POOL   3590CLASS    18,157.9    8.5
Full

This morning I saw reclamation running with this tape mounted and a scratch
tape had just been mounted to, more than likely, move some files. But it's
100% full so I don't get it.

U02188                    NOTES_TPOOL  3590CLASS    36,672.3  100.0    Full

Is this strange and does anyone else have this many tapes with the same
percentage used.
Geoff Gill
TSM Administrator
NT Systems Support Engineer
SAIC
E-Mail:    <mailto:gillg AT saic DOT com> gillg AT saic DOT com
Phone:  (858) 826-4062
Pager:   (877) 905-7154

<Prev in Thread] Current Thread [Next in Thread>