ADSM-L

Re: Problem after time change

2005-10-31 10:40:44
Subject: Re: Problem after time change
From: Leigh Reed <L.Reed AT MDX.AC DOT UK>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 31 Oct 2005 15:21:21 +0000
Farren

There definitely was a client(s) that suffered from this problem and we
logged in over the weekend to ensure that none of our current clients
suffered from the problem. (To be on the safe side)

My recollection was that the clients that suffered were only Windows and
the 2 fix patches were as follows

Ver  3.7.2.17
Ver 4.1.1.16

Looking at the ftp site, your client (5.2.0.6) was released in early
2003, therefore you would think that through 6 clock changes, albeit
only 3 going backwards, somebody would have noticed it if the bug had
been re-introduced, even though it may be specific to your config (ie
W2K3 and NAS). We have a wide range of version 5 clients in existence
and none of them exhibited the bug at the weekend. However, we don't
have 5.2.0.6. Maybe it's worth making a support call to IBM.

If it's any help, I have pasted the text from the original alert readme
from the version 4 client below, it does have some tips on circumvention
or workaround.



A problem with the switch between Daylight Savings Time (DST)

and Standard Time (STD) has just been discovered for the

Windows TSM clients.





BACKGROUND



When Windows NT and 2000 systems automatically switch between

DST and STD, the time attributes for files stored on NTFS file

systems will be shifted by one hour. This is because NTFS

displays time information as an offset from Greenwich Mean Time (GMT).

Thus when the DST change is made, the offset from GMT is changed,

causing the timestamps on your NTFS files to also change.(Note: Time

information for Event Viewer events is affected in the same manner,

but that is not pertinent to this discussion.) Further information on

this subject is available in the Microsoft Knowledge Base, item Q129574.

If you point your web browser to Microsoft's MSDN site,
http://msdn.microsoft.com,

and search on "Q129574" (without the quotes), you will find the
information.





THE PROBLEM



When the system automatically adjusts between DST and STD, the TSM 3.7.2

(and higher) clients will see that the modification time has changed for

all files on NTFS systems, and will proceed to back everything up
accordingly,

even if the file has not really changed. This will occur only once after
the

time change, and thereafter incremental backups will proceed as normal.

However, this will almost certainly affect the amount of data backed up

by each client, effectively causing a full backup on all NTFS file
systems.

This could have a large impact on network and TSM server resources.



The following bullets summarize the conditions under which this problem
can occur:



- TSM client is running on Windows NT 4.0 or Windows 2000. TSM clients
running

  on Windows 9x-based operating systems (Windows 95, 98) are not
affected.



- The TSM client level is 3.7.2.x or higher (including all 4.1.x
levels). TSM

  client levels below 3.7.2.x are not affected, as the problem was
introduced

  in the 3.7.2.x code.



- The file systems are formatted for NTFS. FAT and FAT32 file systems
are

  unaffected by this problem.



- The operating system's time zone settings are configured to
automatically

  adjust for DST. You can check this by right-clicking on the Windows
task

  bar and selecting the "Adjust Date/Time" item in the pop-up menu.

  (Alternatively, you can double-click on the clock display in the task
bar.)

  Either of these actions will bring up the "Date/Time Properties"
dialog.

  Click on the "Time Zone" tab and you should see the "Automatically
adjust

  clock for daylight saving changes" checkbox. If the box is checked
(the

  default installation setting), then your system is configured to

  automatically adjust for DST. Users in regions that do not observe DST

  (such as Arizona) will be unaffected by this problem, provided that
the

  system's time zone settings are similarly configured to not observe
DST.





WHAT IBM/TIVOLI IS DOING ABOUT THIS



Here are the actions that we are taking or have taken to date:



1) We have opened a severity 1 APAR, IC28544, to address this problem.



2) We have designed and built fixtests for the 3.7.2 and 4.1.1 Windows

   clients. The fixtest version numbers are 3.7.2.17 and 4.1.1.17. The

   fixtests should be available in a little while. They will be posted

   to the anonymous FTP server ftp.software.ibm.com in the following
locations:



   Version 4.1.1.17:



   Directory
/storage/tivoli-storage-management/patches/client/v4r1/Windows/v411/sing
le



   Package name start with: IP22088_17





   V3.7 PTF 2:



   Directory
/storage/tivoli-storage-management/patches/client/v3r7/Windows/v372/i386
/single



   Package name starts with: IP21933_17





   A follow-up note will be posted when the fixtests are actually
available for download.



3) Even with the availability of a fixtest, most customers

   will be unable to roll it out in time for the time change.

   We have documented circumventions for this problem (see below),

   as the DST to STD switch is this weekend.



4) We are working on notifying all of our customers in the

   most expedient manner possible.



5) We are continuing our escape and root-cause analyses in

   order to prevent this kind of problem from happening again.





CIRCUMVENTIONS



Here are the known circumventions available thus far:



1) Lock all client nodes to prevent access to the TSM server.

   After the fixtest has been applied to each system, unlock

   that system's node(s). Since many nodes may be affected,

   a batch script may be helpful in facilitating the locking

   and unlocking of the nodes.



2) If the fixtest can not yet be applied, consider using

   the -INCRBYDATE option to back up the clients. The easiest

   way to do this is to add it to existing schedules' options

   setting via the UPDATE SCHEDULE administrator command.



   Example:



     UPDATE SCHEDULE STANDARD DAILY OPTIONS="-INCRBYDATE"



   or if your schedule already contains options, such as -SUBDIR=YES:



     UPDATE SCHEDULE STANDARD DAILY OPTIONS="-INCRBYDATE -SUBDIR=YES"



   Please refer to the Tivoli Storage Manager Administrator's

   Reference for further information on the UPDATE SCHEDULE command.



   Please refer to the Tivoli Storage Manager for Windows Using

   the Windows Backup-Archive Client for further information on

   the -INCRBYDATE option.



3) Same as #1 above, except instead of locking each node,

   disable all client sessions on the TSM server. This is easier

   than having to lock and unlock each node, but would require that

   all affected systems have the fixtest applied before re-enabling

   the server for client sessions.



4) Shut down your TSM server(s) until all affected systems can

   have the fixtest applied.



5) If the additional network and TSM server overhead is not a

   concern, you can just let the backups run to completion. However,

   because this can cause unchanged files to be backed up, the

   oldest version of each affected file will be expired. In order to

   avoid premature expiration, you may wish to add '1' to each

   backup copygroup's VEREXISTS setting. For example, if VEREXISTS

   is currently set to '15', you may wish to change it to '16'. Use

   the UPDATE COPYGROUP and ACTIVATE POLICYSET commands to implement

   this change. Example:



   UPDATE COPYGROUP STANDARD STANDARD STANDARD STANDARD VEREXISTS=16

   ACTIVATE POLICYSET STANDARD STANDARD



   Please refer to the Tivoli Storage Manager Administrator's

   Reference for further information on the UPDATE COPYGROUP

   and ACTIVATE POLICYSET commands.


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Farren Minns
Sent: 31 October 2005 14:40
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] Problem after time change

Hi All

I'm sure this has been covered before and I've been looking on adsm.org
but
haven't found a decent answer yet.

Basically, I'm running TSM Server 5.1.6.2 on Solaris.

The problem client node in question is a Windows Server 2003 Standard
Edition NAS with TSM client 5.2.0.6 running on it. After the clocks went
back at the weekend it has started backing up files that as far as I can
tell have not changed (although I'm not a Windows admin so I may be
missing
something). It doesn't appear to be doing a backup of absolutely
everything
(it managed to check 500,000 files before backing any up), but sadly the
dir it is currently backing up is full of ghost images and is going to
take
a while.

Has anyone else had any similar problems in the past?

Many thanks

Farren Minns
Solaris System Admin / Oracle DBA
IT - Hosting Services


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