Are you talking about a 1TB VOLUME, or several smaller volumes (say
10GB) on a 1TB array? 

H. Milton Johnson
 
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Prather, Wanda
Sent: Tuesday, June 07, 2005 9:07 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Splitting files across tapes

Hi Richard,

Thanks for responding; maybe this will give you something to amuse your
brain over morning coffee.

The reason for the question, mgmt here is considering going to all-disk
backup (for onsite).
So our sequential "volumes" will be disk instead of tape.

We occasionally have issues with mis-classified data ending up on a
tape, and the tape has to be pulled and destroyed.
No big deal with a tape.  Big deal when the "volume" is a 1 TB raid
array!

So the question comes, what is the likelihood that we would contaminate
TWO 1 TB raid arrays with a split file?

I think for sequential volumes, TSM doesn't know that the volume is
full, until it tries to write to it.
If there isn't space for the next "block", then it mounts a scratch and
rewrites the block to a new tape, yes?

So can I assume that the file would have to be larger than an aggregate
(what is that, MOVESIZETHRESH?) in order to end up split across 2 tapes?

Thanks for lending brain power!

W





-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Richard Sims
Sent: Tuesday, June 07, 2005 9:55 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Splitting files across tapes


Hi, Wanda -

I don't believe there is any rule, per se: it is just the case that the
drive finally reaches end-of-volume (EOV - TSM msg ANR8341I).
This results in the subsequent data being written in a spanned Segment
on a new volume.

    Richard Sims

On Jun 7, 2005, at 9:36 AM, Prather, Wanda wrote:

> Does anyone happen to know what rules TSM uses to decide when to split

> a backup file/aggregate across 2 tapes?
> Or can you point me to a document?
>
> (Management wants to know.)
>