Open System Services Management and Operations Guide (G06.29+, H06.07+)
Understanding the OSS File System
Open System Services Management and Operations Guide—527191-005
3-9
Fileset Size Considerations
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The file no longer has a size limit of approximately 2 gigabytes. It can grow to
the size limit for large files.
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Can be moved, copied, or restored to systems running RVUs that do not support
OSS files larger than 2 gigabytes. In such cases, if the file has an underlying
Guardian file format of Format 2 but a size of less than approximately 2 gigabytes:
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The file is automatically converted to use an underlying Guardian format of
Format 1.
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The file becomes subject to the file size limit of approximately 2 gigabytes.
Large Files
These OSS files:
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Are larger than approximately 2 gigabytes.
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Have a size limit of approximately 1 terabyte, constrained by the space available
on the disk volume. For information about the exact size limits, see Appendix E,
Environment Limits.
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Have an underlying Guardian file format of Format 2. This underlying file format is
normally not visible to customer applications.
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Can be accessed using the 64-bit APIs such as creat64( ) and open64( )
only. Depending on the compilation environment, the 32-bit APIs can be
automatically mapped to the 64-bit APIs. The utilities operators use have been
enhanced to support large files. Only application programmers must be aware of
which APIs to use for large files.
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Cannot be restored to systems running RVUs that do not support OSS files larger
than approximately 2 gigabytes.
•
If OSS APIs are used, large files cannot be accessed from systems running RVUs
that do not support OSS files larger than 2 gigabytes. However, Guardian
Enscribe APIs with 64-bit elections can access these files.
Fileset 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.
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
Note. A pax archive file is limited to 8 gigabytes.