The mechanism JBB for Windows uses for monitoring the file system requires
allocating
a buffer to place file system change notifications in.

The Journal daemon file system monitor uses to two threads for monitoring
file system change
activity - one thread for directory name changes (directory creations and
deletions) and one thread for
all other changes.

The size of the notify buffers for these threads are specified by the
NotifyBufferSize and DirNotifyBufferSize
journal configuration settings.

If notification are placed in the buffers faster than the file system
monitor threads can process them a
buffer overflow condition occurs and the journal must be reset since file
system changes have been
missed and the integrity of the journal has been compromised.

Note that a singe file change may generate multiple change notifications,
and each of these notifications
will be placed in the notify buffer and must be processed.

Typically buffer overflows when the file system changes rapidly over a
short period of time, such as when
where large directory trees are copied, deleted, or replicated.

The system load in terms of CPU and memory utilization and the number of
running processes can also
influence the likelihood of buffer overflows as file system monitor
threads will be preempted more and
scheduled less on a heavily loaded system.

In may cases the identical amount of file system change activity on a
lighter loaded system won't cause
buffer overflows which would occur on a more heavily loaded system.

The mechanism file system monitoring mechanism JBB for Unix uses doesn't
suffer this limitation and development
is considering replacing the current Windows mechanism in a future release
but there are no definite plans or
commitments.

Hope this helps .....




Pete Tanenhaus
Tivoli Storage Manager Client Development
email: tanenhau AT us.ibm DOT com
tieline: 320.8778, external: 607.754.4213

"Those who refuse to challenge authority are condemned to conform to it"


---------------------- Forwarded by Pete Tanenhaus/San Jose/IBM on
12/28/2006 11:34 AM ---------------------------
Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
Sent by:        "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
To:     ADSM-L AT VM.MARIST DOT EDU
cc:
Subject:        Re: JBB Notification Buffer overflow ?


On Dec 28, 2006, at 6:18 AM, Otto Chvosta wrote:

> 12/28/2006 09:21:11 ReadFsChangesThread(tid 10236):
> ReadDirectoryChangesW:
> exiting thread due to buffer overflow error.

You can research error messages...
Search for "buffer overflow" at the TSM Support Page
  http://www-306.ibm.com/software/sysmgmt/products/support/
IBMTivoliStorageManager.html

  Richard Sims     http://people.bu.edu/rbs/