ADSM-L

Re: 3592 tape read performance

2006-07-31 15:22:50
Subject: Re: 3592 tape read performance
From: "Kauffman, Tom" <KauffmanT AT NIBCO DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 31 Jul 2006 15:21:37 -0400
There *is* a way to get TSM to stop data movement mid-file. It's ugly.
And I've had to use it in similar circumstances.

Halt the TSM server.

I still don't understand *why* we can't get a cancel process with force
option.

Tom Kauffman
NIBCO, Inc

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Thomas Denier
Sent: Monday, July 31, 2006 3:09 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: 3592 tape read performance

-----"Survoy, Bernard J" <bernard.survoy AT sun DOT com> wrote: -----

>Sounds like you have an issue on some volumes with the VCR (volume
>control region). This structure is used (among other things) to
>support high speed search operations.  If the VCR is invalid or
>damaged, the drive will go into a low speed (essentially sequential
>scan) until you get to the data location you want (takes forever,
>if you look at the drive, it looks like it is reading tape). I know
>on Sun/STK enterprise class drives, we have a similar structure
>called the MIR (media information record); this structure is
>rebuilt during the sequential scan up to the point where you
>successfully locate the data.  A subsequent access beyond this
>point is will rebuild the structure from that point forward.

Just how slow is the linear scan? I am in the process of executing
a 'move data' for a problem volume. The process moved 22 gigabytes
in the first hour or so, and has ostensibly spent almost 5 hours
working on a single 4.7 gigabyte file. How long should I wait for
this one file before I conclude that I have a problem other than
lost VCR information?

What do I do if I decide at some point that the 'move data' is a
lost cause, and want to try 'restore volume' instead? The 'cancel
process' command is cleverly designed to be useless in this sort
of situation; the process will not end until it finishes the current
file. Is there a way to get TSM to stop a data movement process
inmid-file?
CONFIDENTIALITY NOTICE:  This email and any attachments are for the 
exclusive and confidential use of the intended recipient.  If you are not
the intended recipient, please do not read, distribute or take action in 
reliance upon this message. If you have received this in error, please 
notify us immediately by return email and promptly delete this message 
and its attachments from your computer system. We do not waive  
attorney-client or work product privilege by the transmission of this
message.


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