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

Understanding the OSS File System
Open System Services Management and Operations Guide—527191-002
3-8
Relating OSS Files, Filesets, and Disk Volumes
For information on accessing files in the /G directory, see the Open System Services
User’s Guide.
Relating OSS Files, Filesets, and Disk Volumes
You perform OSS file-system configuration and administration tasks through the
Guardian environment. To do these tasks, you need to consider:
•
The sizes of the filesets your site might use
•
How your OSS configuration files are used
Size Considerations
OSS files reside in filesets. A fileset can contain up to 500,000 files as a practical limit.
Filesets reside on disk volumes that are grouped into storage pools. Each fileset has
its own storage pool of one or more disk volumes. A fileset can span multiple disk
volumes.
An individual OSS file cannot span multiple volumes. In the OSS environment, a single
file is always stored on just one disk. While a user cannot extend an existing file for
which no more room is available, the user can readily open a new file in the same
directory on another disk.
As a storage pool’s disk volumes are filled, you can add more volumes to the pool to
accommodate the files in that fileset. Up to 20 disk volumes can be specified as current
members of a storage pool by including them in the storage-pool file for the fileset; the
current members of a storage pool are sometimes called the creation pool, to contrast
them with all of the disk volumes used by the fileset as a pool for file storage.
Fileset size depends mainly on the type and complexity of the application mix running
on your system. If you are porting an application from another system, you would have
some idea of the application’s requirements and could use that as a basis for
estimating the application’s disk-space requirements on the NonStop system.
OSS Configuration Files
The OSS file system gets configuration information from the ZOSSFSET file and
storage-pool files. You configure the OSS file system by updating these files according
to directions in Section 5, Managing Filesets.
The ZOSSFSET File
The names of all filesets defined on the system and information about the disk storage
they use resides in a file named ZOSSFSET, defined in the Guardian environment. The
ZOSSFSET file is completely described under Configuration Files on page 4-6.
When a fileset is mounted, its OSS name server accesses catalog files in the catalog
volume that you specify for the fileset in the ZOSSFSET configuration file.