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Database Administration
Reference : Database Startup Parameters : Alphabetical listing of database startup parameters : Shared memory segment size (-shmsegsize)
 
Shared memory segment size (-shmsegsize)
Operating system and syntax
UNIX Windows
-shmsegsize n
Use with
Maximum value
Minimum value
Single-user default
Multi-user default
DBS
System dependent1
128 for 32-bit systems, 1024 for 64-bit systems.
–
Configuration and system dependent.2
1 Limited by available memory.

2 If not specified, the first attempt is to allocate one segment for all the required memory. If the required memory exceeds the operating system maximum segment size, the system maximum size is used.

n
The maximum number of bytes, specified in MB or GB, in a shared memory segment. The table below lists the supported values by platform.
Table 74. Values for -shmsegsize
Platform
Values in MB
Values in GB1
32-bit platforms
128
–
256
–
512
–
1024
1g
2048
2g
4096
4g
64-bit platforms
1024
1g
2048
2g
4096
4g
8192
8g
16384
16g
32768
32g
1 You must include the "g" if you specify the value in gigabytes.

Use Shared memory segment size (-shmsegsize) to specify the size of the largest shared memory segment the server can allocate. Specifying shared memory segment size can improve performance. Increasing the size of the shared memory segments decreases the number of segments allocated, in turn decreasing the system resources needed to manage the segments. See Sharedmemory allocation for more information.

Notes

*If -shmsegsize is omitted, OpenEdge attempts to fit all shared memory into the fewest segments possible.
*If the total shared memory required is smaller than the value specified with -shmsegsize, only the required amount is allocated.