Not just 100% but very long response times.  You can use iostat to see
response times.






             Remco Post
             <r.post AT PLCS DOT NL>
             Sent by: "ADSM:                                            To
             Dist Stor                 ADSM-L AT VM.MARIST DOT EDU
             Manager"                                                   cc
             <[email protected]
             .EDU>                                                 Subject
                                       Re: [adsm] TSM and XIV

             09/30/2010 11:24
             AM


             Please respond to
             "ADSM: Dist Stor
                 Manager"
             <[email protected]
                   .EDU>






Hmmm,

In that case, wouldn't the disks show 100% busy in nmon? AIX doesn't know
about the XIV back-end processing. And, we also see these pauses on other
TSM servers that are connected to an SVC.

No, I really think that something in TSM is slowing us down...

--

Gr., Remco

On 30 sep. 2010, at 11:20, Lloyd Dieter <ldieter AT ROCHESTER.RR DOT COM> wrote:

> I'm betting the pauses are the XIV destaging data from cache to physical
disk.
>
> Not a big fan of using heavily cached disk LUNs for disk/file storage
pools....
>
>
>
>
> On Wed, 29 Sep 2010 13:47:47 +0200
> Remco Post <r.post AT PLCS DOT NL> wrote:
>
>> Hi all,
>>
>> I'm currently testing TSM 5.5.4 on AIX 5.3 with an IBM XIV box.
>>
>> When I use dd or other tools to copy data off the disk to tape (LTO4),
we
>> get quite a good performance, 100 MB/s or better. Even when backing up
data
>> on the XIV via shared memory directly to tape, we're quite happy, we can
>> read the data at over 100 MB/s for one backup job, and for over 200 MB/s
for
>> two jobs. But, when TSM uses the XIV for DISK volumes, we're not in a
happy
>> place, backing up data from one XIV to TSM with diskpool on another XIV,
we
>> get about 55 MB/s per backup job, best case. Both XIV boxes are
otherwise
>> completely idle. When migrating data of the diskpool to tape, it's the
same,
>> no matter what we do, we don't even get close to the LTO4 native
>> performance, about 70 MB/s is the best I've seen, and usually it's less.
The
>> TSM server is at that time only running the migration, nothing else.
>>
>> The stragest thing we notice is that TSM seems to completely pause every
so
>> often, no disk i/o, no tape i/o no cpu utilization, nothing for about
one
>> second, and the it goes again. When I let two migration processes run,
this
>> is less obvious, because one process continues while the other one
pauses.
>>
>> We've opened a hardware call with IBM to find out if there are any
settings
>> on the hdisks or HBAs that we need to change, and even though we did get
>> some hints, and some performance improvement out of that, we fell that
TSM
>> should be able to do a lot better.
>>
>> Does anyone else have experience with XIV as a diskpool? and if so, what
>> sort of performance do you see?
>>
>> --
>> Met vriendelijke groeten,
>>
>> Remco Post, PLCS
>
>
> --



-----------------------------------------
The information contained in this message is intended only for the
personal and confidential use of the recipient(s) named above. If
the reader of this message is not the intended recipient or an
agent responsible for delivering it to the intended recipient, you
are hereby notified that you have received this document in error
and that any review, dissemination, distribution, or copying of
this message is strictly prohibited. If you have received this
communication in error, please notify us immediately, and delete
the original message.