IC90010: THE OUTPUT IN "DEDUPLICATE DATA NOT STORED" FROM "QUERY STGPOOL F=D" MAY BE NOT CORRECT

APAR status

• Closed as fixed if next.

Error description

• The reporting of deduplication ratios via the Tivoli Storage
  Manager server command QUERY STGPOOL F=D output and occupancy
  table might be inaccurate. The reason being is that deduplicated
  chunks of data which are used as base data for same data
  matches, might not be included in the calculations. Since these
  data chunks are truly occupying storage space they should cost
  against the deduplication ratio value and in some cases, they
  are not.
  
  The result is that the deduplication ratio might be slightly
  higher than reality.
  
  Customer/L2 Diagnostics :
  The best way to show an example is by using an the output from
  the "tsm_dedup_stats.pl" script. This is attached in the
  tech note 1596944:
  
  Determining the impact of deduplication on a
  Tivoli Storage Manager server database and storage pools
  http://www-01.ibm.com/support/docview.wss?uid=swg21596944
  
  This can be used to get deduplication information and stats for
  a given environment. Here is an example from the script output
  that shows the stgpool utilization information:
  
  Pool: DEDUP-POOL
    Type: PRIMARY    Est. Cap. (MB): 11372626.3 Pct Util: 64.7
    Reclaim Thresh: 100 Reclaim Procs: 1            Next Pool:
    Identify Procs: 2   Dedup Saved:9273226
  
  
    Logical stored (MB):   5285872.39
    Dedup Not Stored (MB):  9273226.86
    Total Managed (MB):  14559099.25
  
    Volume count:      228
    AVG volume size:    49879
    Number of chunks: 52501740
    Avg chunk size:   342824
  
  The storage utilization of the storage pool does not match with
  the logical value (+ reclaim pct) of the storage pool.
  
  11372626 * 64% = 7.3 TB
  
  The percent reclaim for this environment was 412 GB
  
  The following server select command shows:
  
  select sum(est_capacity_mb*pct_reclaim/100) as
  "Reclaimable (MB)"  from volumes where stgpool_name='DEDUP-POOL'
  
  Reclaimable (MB) = 412GB
  
  
  Logical Stored + Reclaimable = 5.7 TB
  
  At this point, there is 7.3 TB of used space in the storage
  pool but we are only accounting for 5.7 TB. A good portion of
  the rest of that space is deleted base chunks which are no
  longer assigned to client files (they have been expired).
  
  Tivoli Storage Manager Versions Affected:
  Tivoli Storage Manager Server version  6.1, 6.2 and 6.3 on all
  platforms
  
  Initial Impact:
  low
  
  Additional Keywords:
  TSM zz61 zz62 zz63 dedup
  

Local fix

• Run the following DB2 command to get the "real" values:
  
  db2 "select cast( sum(bfaa.lsize)/(1024*1024*1024) as
  decimal(10,2) ) as LOGICAL_OCC_GB,
  cast( sum(bfaa.rsize)/(1024*1024*1024) as decimal(10,2) ) as
  MANAGED_OCC_GB from bf_aggregate_attributes bfaa left join
  af_bitfiles afbf on (afbf.srvid=bfaa.srvid and
  afbf.bfid=bfaa.superbfid) where bfaa.srvid=0 and
  afbf.poolid=<poolid>"
  
  The storage pool id <poolid> can be captured via the server
  SHOW command: show sspool
  The number in brackets after the storage pool name is the
  poolid
  
  The above will give the true logical and reporting
  (before dedup). The LOGICAL value here can be added to any
  reclaimable space and it should get us close to the storage
  pool utilization.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Tivoli Storage Manager server users.     *
  ****************************************************************
  * PROBLEM DESCRIPTION: See error description.                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  This problem is projected to be fixed in a future version of
  the
  Tivoli Storage Manager server.  Note that this is subject to
  change at the discretion of IBM.
  
  
  Affected platforms:  AIX, HP-UX, Solaris, Linux, and Windows.
  

Problem conclusion

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels

• R61A PSY

     UP

• R61H PSY

     UP

• R61L PSY

     UP

• R61S PSY

     UP

• R61W PSY

     UP

• R62A PSY

     UP

• R62H PSY

     UP

• R62L PSY

     UP

• R62S PSY

     UP

• R62W PSY

     UP

• R63A PSY

     UP

• R63H PSY

     UP

• R63L PSY

     UP

• R63S PSY

     UP

• R63W PSY

     UP