Open System Services Management and Operations Guide (G06.25+, H06.03+)

Introducing Open System Services
Open System Services Management and Operations Guide—527191-002
1-11
Interprocess Communication Facilities
An OSS file manager process named $ZFMnn runs in each processor (nn indicates
the processor number). The OSS file manager starts automatically when the processor
starts; if the OSS file manager terminates abnormally, it takes down the processor. Its
processor can be shut down without first stopping the process, but you should stop all
applications with open OSS files first.
The OSS file manager automatically:
•
Allocates and initializes the PXS extended segment and OSS file-system cache
•
Satisfies OSS regular file cache-related requests from disk processes
The PXS extended segment is used to share OSS file-system data structures within
that processor. The PXS extended segment is created and managed without system
manager or operator intervention.
The OSS file-system cache is used to buffer data transfers between the OSS disk files
and an OSS application. Whether this cache is used for a specific file depends on:
•
Options used by an application to open the file
•
The setting of the OSSCACHING flag for the disk process of the disk volume that
contains that file
See Changing OSS File Caching for the Disks of a Fileset on page 5-16 for more
information on configuring this cache.
Disk processes also can use data caches, as shown in Figure 1-4 on page 1-10. The
use of disk process caching determines whether OSS file-system caching can be used,
as mentioned above. See the Storage Subsystem Configuration and Management
Manual for additional information about disk process caching.
An OSS name server also maintains a cache of the most recently resolved names for
its filesets. This cache has a default size of 4096 inode values and 4096 link values.
Other cache sizes can be specified through Subsystem Control Facility (SCF)
commands, as described under Configuring an OSS Name Server on page 4-27.
OSS resources such as the PXS extended segment, data cache, OSS name server
inode cache, and link cache, can also be monitored using Measure. See the Measure
Reference Manual for information about the OSSCPU and OSSNS entities.
Interprocess Communication Facilities
Open System Services provides a set of interprocess communication (IPC) facilities
identical to those of the UNIX operating system. The OSS IPC facilities are separate
from the IPC facilities supplied within the Guardian environment.
OSS IPC facilities include the facilities described in the following subsections:
•
OSS Shared Memory and Semaphores on page 1-13
•
OSS Message Queues on page 1-14
•
Pipes and FIFOs on page 1-14
•
OSS Sockets on page 1-14