Chapter 2 HPSS Planning124 September 2002 HPSS Installation GuideRelease 4.5, Revision 2Avg. Text OverflowsPer Name SpaceObjectA name-space object record can store a filename that is 23 characters long (the basename, not the full pathname). If a filename is longer than 23 characters, a text overflowrecord must be generated. Also, if a comment is attached to a name-space object, a textoverflow record must be created. This value defines, on average, how many textoverflow records will be created per name-space object. For example, if 5 in 100 name-space objects will either have a filename longer than 23 characters or a commentattached, a value of .05 would be entered.Avg Length of TextOverflowsThis is the average length of each name space object which will exceed 23 characters.This value in conjunction with “Avg Text Overflows Per Name Space Object” is usedto determine the amount of metadata in ‘nstext’ required to store all text overflows.This value can significantly impact the size of the metadata estimate.Filesets per NameServerThe number of filesets a Name Server will be managing.Avg. BitfileSegments Per TapeBitfileThe average number of bitfile segments created for each tape bitfile. When files aremigrated to tape from disk, there normally will be only one tape bitfile segment for thefile. However, if the file is partially modified, additional bitfile segments will bemigrated to tape. This value significantly impacts the overall metadata sizing estimate.Avg. StorageSegments Per DiskVVThe average number of storage segments that will be created per disk virtual volume.Since there are a maximum of 16,384 blocks per disk VV, and each storage segmentuses one or more VV blocks, the number must be less than or equal to 16,384. Thisvalue can be determined by dividing the average disk VV size by the average storagesegment size.Avg. StorageSegments Per DiskAlloc RecEach disk allocation record stores information for up to 8 disk storage segments. If, onaverage, 1 extra disk allocation record is required per 5 disk bitfiles, a value of 1.2would be entered.Avg. StorageSegments Per TapeBitfileThe average number of storage segments per tape bitfile. If files are only written to tapethrough migration, the value can be 1, assuming the storage class characteristics havebeen set up properly. If users are allowed to write directly to tape, the average should besomething higher than 1.Max BFS StorageSegmentCheckpointsThe maximum number of storage segment checkpoint records created by BFS. A valueof 500 should be sufficient for planning purposes.Max Queued BitfilesChanging COSThe maximum number of bitfiles that have a pending class of service change. A valueof 1,000 should be sufficient for planning purposes.Max Queued BFSStorage SegmentUnlinksThe maximum number of storage segments that could be queued to be unlinked. Avalue of 1,000 should be sufficient for planning purposes.Max Disk BitfilesQueued forMigrationThe maximum number of unmigrated bitfiles that may exist on disk at one time. Thevalue should generally equal Max Bitfiles on Disk.Max Disk BitfilesQueued for PurgingThe maximum number of migrated bitfiles that may exist on disk at one time. Thevalue should generally equal Max Bitfiles on Disk.Table 2-6 HPSS Dynamic Variables (Continued)(Subsystem Specific)Variable Description
