Minimum ulimits

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The directory server tries to enforce minimum ulimit option values that are important for the smooth running of the server.

During startup, the directory server verifies whether the ulimit option values for the current process are greater than or equal to the prescribed ulimit option values specified in the configuration file. If the verification fails, then the server attempts to set the ulimit option values of the current process to the prescribed values. If the server fails to do so, it starts in configuration only mode.

The following list shows all the typical ulimit options whose values are critical for the smooth running of the directory server.

Note: The ulimit options are applicable only to the proxy and back-end servers. No minimum ulimit options values are prescribed for the admin server process.

Critical memory parameters
Virtual memory size: This option includes all types of memory that includes stack, heap, and memory-mapped files. Attempts to allocate memory in excess of this limit fails with an out-of-memory error. The value for this option is specified in kilobytes.
Maximum resident set size (RSS): This option limits the amount of memory that can be swapped in to physical memory on behalf of any one process. The value for this option is specified in kilobytes.
Note: AIX® defines this ulimit option, while Solaris does not specify this option.
Data segment: This option limits the amount of memory that a process can allocate to a heap. The value for this option is specified in kilobytes.
Stack size: This option limits the amount of memory a process can allocate to a stack. The value for this option is specified in kilobytes.
Critical File parameters
File size: This option limits the maximum size of a file that a process can create. This is specified in 512-byte blocks.
Nofile: This option limits the number of file descriptors that belong to a single process. File descriptors include not only files but also sockets for Internet communication.
Note: On Solaris, the number of open files limit is set to the hard limit of the number of open files when the server is started. The number of open files limit cannot be changed by using the ulimit feature.

The following table lists the operating system default values and the prescribed minimum ulimit values of the critical options.

Table 1. System-specific ulimit values
ulimit Option	AIX		Solaris
	`operating system default`	`prescribed minimum`	`operating system default`	`prescribed minimum`
Data segment size	256 MB	256 MB	Unlimited	256 MB
Virtual memory	Unlimited	1 GB	Unlimited	1 GB
Nofile	2000	500	256	256
Maximum resident set size (rss)	64 MB	256 MB	N/A	N/A
File size	1024 MB	1024 MB	Unlimited	1024 MB
Stack size	64 MB	64 MB	8 MB	8 MB

Table 2. System-specific ulimit values
Ulimit Option	Linux®
	`operating system default`	`prescribed minimum`
Data segment size	Unlimited	256 MB
Virtual memory	Unlimited	1 GB
Nofile	1024	500
Maximum resident set size (rss)	N/A	N/A
File size	Unlimited	1024 MB
Stack size	10 MB	10 MB

Note: Operating system default ulimit option values might vary for different kernel versions and for different shells in the same kernel version.

An administrator can modify the minimum ulimit option values by using the web administration tool or through the command line.