An interesting source of tape drive performance data is the TSM server
itself, in the SUMMARY table.
Extract it with SELECT into a comma-delimited or tab-delimited file, and
then read it in to any popular statistical program like SPSS or SAS. You
have to match up the records for processes such as MIGRATION,
RECLAMATION, MOVE DATA... with the corresponding TAPE MOUNT records to
track it down to the individual drive, but that's not rocket science in
a stat program. Subtract media wait time, and you've got pretty good
tape drive performance informaiton.
Every day, I have a cron process that extracts the previous day's
SUMMARY data into a file. But for exploration, you could simply extract
the entire 30-days SUMMARY table into a file and then work that over
with SAS or SPSS to get some very intersting stats.
This is, of course, measuring only end-to-end tape subsystem speed.
There is no way to separate out the bus, controllers, the drives, etc.
But since you are collecting all of it, rather than spot anecdotal
measurements, and since you do have specific drive names in the data, it
gains quite a bit of statistical validity. You can also correlate the
data with what kind of operation it is e.g. migration, reclamation, move
data, client backup, etc.
A distinct advantage is that it requires no instrumentation other than
the TSM server itself, so you can get this data in brain-dead systems
like Windows just fine. Another distinct advantage of this data source
is that it's measuring it where it really matters - how much data TSM
actually can push through that pathway. Therefore it's easy to track
whether changes such as splitting drives out among multiple controllers,
helps or not.
P.S. I like AIX systems for TSM servers too. The best server system for
large data I/O throughput. If you don't use AIX, you'll find yourself
splitting servers much earlier, and into far more small pieces.
Roger Deschner University of Illinois at Chicago rogerd AT uic DOT edu
====== "If you torture the data long enough, they will confess." =======
On Fri, 27 Feb 2009, David Bronder wrote:
>Wanda Prather wrote:
>>
>> And there is NO instrumentation in Windows to give you any idea whatever
>> about what is going on performance-wise on a bus with tape drives attached.
>
>Unfortunately, there doesn't seem to be any real instrumentation in AIX
>about tape drive performance, either. None of the standard AIX tools
>seem to give tape-related information (e.g. iostat or nmon), either for
>the tape drives themselves or for the buses or adapters the drives are
>connected to (unless there is also disk behind those buses or adapters).
>(Speaking only of FC drives, since the last time I used SCSI tape drives
>years ago, I never tried to get that data.)
>
>So far, neither IBMers nor business partners I've talked to have been
>able to identify a way of collecting that kind of data, either. The best
>ideas I've been able to come up with are manual timing tests (measure the
>time to transfer a known volume of data, whether within TSM or externally)
>or to look at stats on the fibre ports on the SAN switches (assuming one
>has that kind of access to the switches).
>
>If anyone can tell me differently, I'd love to hear about it. Even if
>(especially if?) it's something dead simple or obvious that I've been
>missing.
>
>=Dave (sticking with AIX for TSM for the forseeable future)
>
>--
>Hello World. David Bronder - Systems Admin
>Segmentation Fault ITS-SPA, Univ. of Iowa
>Core dumped, disk trashed, quota filled, soda warm. david-bronder AT uiowa
>DOT edu
>
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