IMPORTANT - PLEASE READ THE FOLLOWING: 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/single 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. We apologize for the inconveniences caused by this problem. Sincerely, Andy Raibeck IBM/Tivoli Tivoli Storage Manager Client Development e-mail: [EMAIL PROTECTED] "The only dumb question is the one that goes unasked."
