ADSM-L

? Should we set Resourceutilization > 10 if appropriate ?

2006-06-05 17:45:27
Subject: ? Should we set Resourceutilization > 10 if appropriate ?
From: James R Owen <Jim.Owen AT YALE DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 5 Jun 2006 17:45:00 -0400
Andy, et al.
[Is anyone out there using RESOURCEUTILZATION n w/ n > 10 ??]

Andy Raibeck's presentation @ Oxford's 2001 TSM Symposium
        http://tsm-symposium.oucs.ox.ac.uk/2001/papers/
        Raibeck.APeekUnderTheHood.PDF
includes this table showing what will result from setting:

RESOURCEUTILIZATION n Max.Sess. ProducerSess. Threshold(Seconds)
--------------------- --------  ------------  ------------------
        <default> 2               1               30
        1               1               0               45
        2               2               1               45
        3               3               1               45
        4               3               1               30
        5               4               2               30
        6               4               2               20
        7               5               2               20
        8               6               3               20
        9               7               3               20
        10              8               4               10
 (undocumented:
        11<=n<=100)       n               0.5n            10

and also includes these warnings:
Undocumented, internal values subject to change without notice.
RESOURCEUTILIZATION > 10 is unsupported.

Management discourages use of undocumented/unsupported settings,
but I'm arguing that we need to specify RESOURCEUTILIZATION 30
in order to effect efficient backups for our email servers:
        4 IMAP servers, each w/4 CPUs, running linux client 5.2.3,
        each backs up 15 FS sending ~200GB/night (compressed)
        via 100Mb -> Gb ethernet
        to our TSM 5.2.3 service's disk stgpool

With RESOURCEUTILIZATION 10 specified, we never see more than 8
simultaneous FS backups, and some of 8 large IMAP filesystems are
always the last backups to start, serially after other smaller FS
backups complete!  Testing w/ RESOURCEUTILIZATION 30 causes one
client to start up 31 sessions enabling all 15 FS backups to start
essentially simultaneously.  I expect the smaller FS backups will
complete first w/ the 8 larger IMAP FS backups completing later, but
w/ all FS backups for each client finishing faster because none will
wait to start serially after other FS backups because insufficient
backup sessions were started.

Asking only for your own advice, recognizing IBM probably does not
allow you recommend using unsupported/undocumented optional settings:

Is my understanding of the unsupported/undocumented setting (w/ N>10)
correct?  Are we risking some unanticipated problems trying to use
RESOURCEUTILIZAION 30 to backup all four of these email servers
simultaneously?  [I believe we have sufficient network bandwidth,
disk I/O capacity and CPU's for TSM clients and service.]

Is there some important reason that IBM did not choose to document
and support N>10 for RESOURCEUTILIZATION?  [The higher settings would
seem to be useful and appropriate for some high-bandwidth circumstances,
or did I miss something?]

Is there a simple way to specify the order in which FS are selected for
backup when multi-threading is active?

Thanks [hoping] for your advice!
--
Jim.Owen AT Yale DOT Edu   (203.432.6693)

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