Date: 21/09/2006
NV Version: 7.4.x
OS Version: Windows 2000, Windows 2003, Windows XP
Plugin version: OFM ALL
Description:
Explanation of why OFM might fail to synchronize certain drives
Symptoms:
Certain drives fail to be synchronized by OFM during a backup and the following error can be found in the log:
Warning 2006/08/09 20:05:06 147 Data Plugin - Will not use OFM for anything on drive 'C:\'. Failed to synchronize drive
For each backup, OFM needs to find a period of time (Write Inactivity Period, WIP, default 3 seconds) for the OFM driver to synchronise on the server. If there is no WIP available, OFM will fail to synchronise certain drives, which will cause the backup to 'complete with warnings/errors'.
This is caused by the fact that OFM driver needs a period of time (WIP) of a minimum of 1 second to synchronise the server during backup. The first step is to specify the lowest WIP possible - 1 second with a newer ofmldrv.sys and a modified ofm.cfg, both of which can be obtained from support. However, on very busy systems, even this amount of time can be too long. It is vital to find a period of time where there isn't any activity on the server so that OFM can synchronise.
If the system is constantly busy (for instance a database constantly running in the background), a workaround is to create a list of files not to synchronise. This is refering to the "Files to exclude from synchronization" field on the backup options tab of a filesystem APM backup. This field is only visible when the OFM driver is installed.
The information to enter here is a comma-separated list of file such as:
"c:\db1.mdf,c:\db1.ldf".
This field will then tell OFM to synchronise the drive regardless if writes are occurring during the WIP timeout to those files.
One useful free utility that can be run is "Filemon" available from sysinternals.com which shows what files are being written to at any particular moment in time, so that we can see which files are most active.
It is also important to check that there isn't any other Open File Management software installed as it will interfere with OFM. For example, Backup Exec ships with its own Otman5.sys that might be left behind on uninstallation. This can be verified by checking the registry tree "HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\SERVICES\OTMAN5" - other software should be visible in a similar location. Otman can be removed by following the Veritas KB article available here: http://seer.support.veritas.com/docs/270279.htm
Prepared by: Sonia De Menditte, Modified by Nils Krumrey
