Limit Domino shared memory usage by backup applications in order to prevent
a server crash.
When a third party backup application begins a backup of an NSF file, each
update to that NSF results in Domino recording (in shared memory) the "before
image" state of the block on disk being updated. This continues
until the backup application has completed backing up the NSF.
The use of scheduled agents, running compact, fixup, updall, or any other
maintenance task that could produce a massive amount of updates to an NSF
that is also being backed up may result in Domino storing too much disk
state information in shared memory. This eventually results in all
addressable virtual memory for the process being exhausted. Domino
eventually panics when this occurs. For example, a crash could
occur when an agent modifies many documents while Tivoli Data Protector
(the domdsmc task) backs up the same large database.
By implementing the NOTES.INI setting NSF_BACKUP_MEMORY_CONSTRAINED=1 the
amount of memory used by the backup application can be limited. To change
the default limit of 20MB, the NSF_BACKUP_MEMORY_LIMIT=bytes setting can
be used, where 'bytes' is the memory limit defined in bytes.
Example: NSF_BACKUP_MEMORY_LIMIT= 104857600 (for 100 MB)
IBM recommends not setting this parameter above 300 MB. Keep this
parameter set to the default value until you determine that the default
value is not sufficient. Start setting this parameter to 100 MB.
This setting can be dangerous if set too high. Do not set this
value below the default of 20 MB.
When NSF_BACKUP_MEMORY_CONSTRAINED is absent or set to 0 this memory constraining
feature is disabled.
When NSF_BACKUP_MEMORY_CONSTRAINED is enabled and NSF_BACKUP_MEMORY_LIMIT
is absent the default memory size if 20 MB.
Enable NSF_BACKUP_MEMORY_CONSTRAINED on any Domino servers running backup
applications which use Domino shared memory.
When NSF_BACKUP_MEMORY_CONSTRAINED is enabled, NSF_BACKUP_MEMORY_LIMIT
may be used but should be within the range of 20 MB - 300 MB.
This behavior applies to Domino 6.5.6, 7.0.2 and beyond.
The Domino server must be restarted after modifying this setting
crashes due to low memory condition after backup application runs
Domino Configuration Tuner:
This setting is included in the DCT
catalog of best practices.