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00553: Unix operating system parameters that impact PRO/5


Unix operating system parameters that impact PRO/5


There are several Unix configuration parameters which can affect your PRO/5 installation. These deal with system limits affecting: the maximum size of files, the maximum number of files that can be opened at one time, the maximum number of locks that can be active at one time, and the amount of system memory allocated to disk buffers. These parameters must be set properly in order for your system to function in an efficient manner. What follows is a brief discussion of these parameters. Their names and the methods of setting them vary from system to system. Please consult your Unix manuals for the correct names and procedures for your system. 

Determines the maximum number of blocks that can be written to a file. On most systems this parameter can be set in your login profile. Check with your system administrator for the settings on your system. This number should be set large enough to handle the largest files you expect to write. If ULIMIT is not set high enough you could experience PRO/5 !ERROR=2s or !ERROR=15s when writing to large files. 

A special program, pro5run, is supplied with PRO/5 for most Unix operating systems. This program will attempt to set ULIMIT to a very large value for your system before overlaying itself with PRO/5. This may be necessary on some systems where the ULIMIT is not easily changed by a user. ULIMIT can be set as a system parameter in most systems. It can usually be set as well by an individual process. 

Sets the total number of file handles that can be OPENed at any one time on the system. This should be set to at least the average number of files used per task, times the number of tasks you are running. If you are using FCBCACHE, this number should be increased to reflect the number of active files as well as the number of cached files. If this number is set too low, PRO/5 !ERROR=16s may occur on the system. If it is set too high, system performance can suffer because system memory is being tied up for files tables that are not being used. NFILES is usually set as a system parameter. 

Sets the total number of locks that can be active at anyone time. PRO/5 uses locks to arbitrate record usage. A rule of thumb to follow in setting this parameter is to allow one lock per open PRO/5 file plus one per PRO/5 task, plus any other locks required by other tasks. If a PRO/5 task requests a lock and none are available, an !ERROR=0 could be generated. In some cases that task requesting the lock can hang. In most cases, system performance will be noticeably affected. 

Sets the number of memory blocks allocated to disk buffers. System performance is greatly dependent on this parameter. If it is set too low, the system has to access the disk more often, slowing the system down and can cause problems opening a large number of files systemwide. If it is set too high, time could be wasted searching in memory for disk blocks that have not been read. A rule of thumb is to allow approximately 25% of the system memory for buffers. 

A hangup signal in the Unix operating system (SIGHUP) will cause an orderly shutdown of PRO/5. Pending terminal output and pending terminal reset operations are terminated. An illegal instruction signal (SIGILL) will be treated the same as an interrupt character (SIGINT) and (SET ESCAPE), even when PRO/5 is not running on a terminal. 

1996 BASIS International Ltd. All rights reserved. 

Last Modified: 02/23/2004 Product: PRO/5 Operating System: Unix

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