Hi Everyone,

As we have been implementing our two new DD boxes we have been
setting them up like our existing two DD boxes - file devices
with the pool NOT collocated.  This is what DD recommends and
it seems to work very well this way.

But, I've been thinking about collocating anyway!

I was poking around the DD command line and found that you
can get the dedup/compression information for any individual
directory or file.  For example, below is the dedup/comp
factors for a file volume in a pool with one node I'm testing with:

  rsbkup:/tsmdata/tsm_scripts==>./run_cmd.ksh tsm2 "q nodedata WVLOGS01P"
| grep isdd2260
  WVLOGS01p    /isdd2260/tsm2/test/0002267E.BFS        TEST-PRI-ISDD2260
 30,551.83
  WVLOGS01P    /isdd2260/tsm2/test/0002267F.BFS        TEST-PRI-ISDD2260
 30,621.15
  WVLOGS01P    /isdd2260/tsm2/test/00022680.BFS        TEST-PRI-ISDD2260
 30,601.55
  WVLOGS01P    /isdd2260/tsm2/test/00022682.BFS        TEST-PRI-ISDD2260
 30,604.08
  WVLOGS01P    /isdd2260/tsm2/test/00022683.BFS        TEST-PRI-ISDD2260
 30,620.86
  WVLOGS01P    /isdd2260/tsm2/test/00022684.BFS        TEST-PRI-ISDD2260
 4,731.24

  rsbkup:/tsmdata/tsm_scripts==>./run_cmd.ksh tsm2 "q vol
/isdd2260/tsm2/test/0002267E.BFS"
  /isdd2260/tsm2/test/0002267E.BFS        TEST-PRI-ISDD2260       TEST
30.6 G  100.0   Full

  sysadmin@isdd2260# filesys show compression
/data/col1/tsm2/test/0002267e.bfs
  Total files: 1;  bytes/storage_used: 4.6
         Original Bytes:       32,332,636,620
    Globally Compressed:       30,695,597,675
     Locally Compressed:        6,930,888,022
              Meta-data:           98,615,480

In this case, this vol is getting a 4.6x overall dedup/comp factor.

So, if I collocate the pool in TSM I should be able to use "q nodedata
<node>" to get a list of vols used by a node, then I can query the DD to
get the dedup/comp stats for that node.  A little scripting and I can
generate a report of dedup/comp ratios by TSM node.  This would help us
maintain which nodes make sense to put/keep on the DD.

Just curious if anyone is using collocation for a DD file pool?  To do so
would use more volumes and more filling volumes, but I can't think of any
real reason to not collocate.

Rick




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