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
3-11
OSS Configuration Files
receives a file-creation request, the server reads the storage-pool file and creates the
file on the disk volume whose name appears in the storage-pool file following the
volume name used for the last request.
As each new file is created, the fileset’s OSS name server continues along the list of
volume names, selecting a new volume with each request. The OSS name server
ultimately wraps around to the beginning of the list in a round-robin fashion.
Thus, if users write only small files in one disk volume in the list and only large files in
another, then one volume can fill up before the others. By allocating a large enough
fileset, you can help avoid the problems produced by this unlikely file distribution.
An OSS name server cannot allocate files on more than 20 disk volumes for one
fileset. However, each time a fileset is mounted, you can specify either:
•
A different set of disk volumes for the creation pool of the fileset (different content
of the same storage-pool file)
•
A different storage-pool file for the fileset, containing a different set of disk volumes
As a result, a fileset can span many disk volumes. OSS files can exist on disk volumes
that are part of the fileset even though they are not in any active storage-pool file. The
storage pool for the fileset can be much larger than the creation pool defined by the
content of the storage-pool file.
For this reason, a storage-pool file cannot contain more than 20 active volume names
(the creation pool) but the volume list maintained by an OSS name server for the fileset
(the entire storage pool) can contain up to 256 disk volumes. See FSCK Log File on
page 5-25 for more information about the volume list.
You should not set up a fileset to use a disk volume that is not always in the storage-
pool file for that fileset. Normal operating procedures for a fileset can have unplanned
side effects on the OSS files on such disk volumes. See Changing the Physical
Makeup of a Fileset on page 5-21 for more information.