Looking to mail user - you love tsm, not the news :-()
The bad news: this problem might affect any SAN tape operation!!! Be it
over LAN with TSM server writing to SAN tape, be it LAN-free with storage
agent, even with "competitive" product (the problem was introduced by
QLogic; IBM, Legato and Veritas were some of the affected parties)!!!
It is even harder to track and detect the problem and its impact as you
can have different settings on different systems. For example, TSM server
might have old driver with default value of 0x41, while newly installed
storage agent might be with 0x21 and corrupted LAN-free backups.
If we bring the change management in the equation the things are getting
even worse. Example: same TSM server (old driver, 0x41) using LTO1 drives
was connected to upgraded fabric with bigger SAN switches and the driver
got upgraded - you may introduce a problem into formerly working
environment.
etc, etc...
Go and investigate:
- when the TSM was installed?
- who have installed it?
- which version of the driver did he/she used?
- was he/she aware of the MaximumSGList issue and was the value increased?
- was the SAN changed?
- was the Windows service Packed with driver update?
...
And do not forget to inform the management! You will have some sleepless
nights, let them share your glory.
Zlatko Krastev
IT Consultant
i love tsm <[EMAIL PROTECTED]>
Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
30.10.2003 17:06
Please respond to "ADSM: Dist Stor Manager"
To: [EMAIL PROTECTED]
cc:
Subject: Re: maximumsglist - lanfree
So just for my clarity
This affects all data written to the LTO drives, it doesn't matter whether
its data from normal LAN backups or LAN Free backups.??
In effect all my backups taken in the last year are potentially not fully
restorable.....
I would love you to tell me the above is wrong
What a nightmare this could turn out to be !!
>From: Zlatko Krastev <[EMAIL PROTECTED]>
>Reply-To: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: maximumsglist - lanfree
>Date: Thu, 30 Oct 2003 14:27:24 +0200
>
>Chris,
>
>Nearly two years ago (during the TSM 4.2 era) QLogic changed the default
>value of MaximumSGList option from 0x41 to 0x21. This option mandates how
>large your FCP packets can be. If you were receiving errors when packet
is
>larger than the limit, you will now during backup time there is an
>inconsistency. The real issue is that data is falsely reported as
>successfully sent but is truncated.
>
>Large blocks are used mostly for tape storage. Thus disk operations are
>not affected (and no problems are reported there). But tape operations
are
>affected and you can realize this usually long after the problem
>happened!!
>
>Answering to your question - increasing the value *does not* affect the
>disk operations. Assume the option equivalent to Maximum Transmit Unit
>(MTU) for LANs - you can send (shorter) disk frames and they will be
under
>the limit. If limit is high enough, the (longer) tape frames will also be
>within it, and no data will be lost/corrupted.
>
>Zlatko Krastev
>IT Consultant
>
>
>
>
>
>
>i love tsm <[EMAIL PROTECTED]>
>Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
>30.10.2003 12:50
>Please respond to "ADSM: Dist Stor Manager"
>
>
> To: [EMAIL PROTECTED]
> cc:
> Subject: Re: maximumsglist - lanfree
>
>
>Zlatko
>
>thanks for your response.......we have been running our tsm server for a
>year with maximumsglist at the default value.... if what your saying is
>true about restore capability that would explain a few things.. we have
>done
>major restores and not got all the data back we expected. Is there an
IBM
>document on all this somewhere other than IBM flash 10135?
>
>Another question, our tsm server has multiple qlogic hba's. I believe
the
>maximumsglist will take affect on all the adapters. However some of
those
>adapters are used just for SAN disk connectivity. Will changing this
>parameter have any impact on disk access/performance?
>
>Thanks again
>
>Chris
>
> >From: Zlatko Krastev <[EMAIL PROTECTED]>
> >Reply-To: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED]
> >Subject: Re: maximumsglist - lanfree
> >Date: Thu, 30 Oct 2003 10:31:30 +0200
> >
> >You must set this option higher than 0x41 (I prefer 0xFF) on *any*
>machine
> >accessing tape over SAN - be it TSM server, TSM Storage Agent, or any
> >other product.
> >Afterwards you must perform the backup *again* - some times with low
> >maximumsglist setting the data is reported to be written but is not
> >completely. Thus your backup might be not restoreable.
> >
> >Zlatko Krastev
> >IT Consultant
> >
> >
> >
> >
> >
> >
> >i love tsm <[EMAIL PROTECTED]>
> >Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
> >30.10.2003 09:21
> >Please respond to "ADSM: Dist Stor Manager"
> >
> >
> > To: [EMAIL PROTECTED]
> > cc:
> > Subject: maximumsglist - lanfree
> >
> >
> >Hi
> >
> >Well the quest for lan free backups continues....
> >
> >I got past my initial problems by upgrading storage agent to 5.1.5.4
>(same
> >level as server)
> >
> >Yesterday I managed to run an image backup lan free, 150Gb in 1hr 15
> >minutes
> >so was quite happy with that. However when I went to restore it 5
>minutes
> >later it failed and the server actlog gave me
> >
> >10/29/2003 16:39:39 ANR8939E The adapter for tape drive DRIVE2WWPK
> >(mt1.0.0.5)
> > cannot handle the block size needed
to
> >use
> >the volume.
> >
> >I then tried another image backup and it failed with the same error.
> >During
> >the time of the image backup working then stopping working nothing had
> >changed.
> >
> >I believe the above error is to do with the registry entry for
> >maximumsglist. On the storage agent client I have had maximumsglist
set
> >to
> >FF for a while.
> >
> >My question is do I need to set the same registry key on the TSM Server
> >itself?
> >If not then what else can be causing this
> >
> >TIA
> >
> >_________________________________________________________________
> >It's fast, it's easy and it's free. Get MSN Messenger today!
> >http://www.msn.co.uk/messenger
>
>_________________________________________________________________
>Find a cheaper internet access deal - choose one to suit you.
>http://www.msn.co.uk/internetaccess
_________________________________________________________________
Find a cheaper internet access deal - choose one to suit you.
http://www.msn.co.uk/internetaccess
