ADSM-L

Re: [ADSM-L] [adsm] TSM and XIV

2010-09-30 05:21:02
Subject: Re: [ADSM-L] [adsm] TSM and XIV
From: Lloyd Dieter <ldieter AT ROCHESTER.RR DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Thu, 30 Sep 2010 05:20:10 -0400
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


--

<Prev in Thread] Current Thread [Next in Thread>