Space requirement for HSM control files

The Space Management client creates control files which require free space on the system. Without sufficient free space, HSM cannot run properly.

Most files in the .SpaceMan directory occupy approximately 1 GB of space. In addition to this basic requirement, there are some files that can occupy significantly more space.

.SpaceMan/metadata

If the scout daemon is running, the daemon creates the complete file index (CFI). The scout daemon runs when you set hsmdisableautomigdaemons=no (the default value). The CFI requires approximately 1 KB per file system block or file. For example, if the file system size is 1 TB, and the block size is 1 MB, there are 1,000,000 blocks on the file system. Multiply 1,000,000 blocks by 1 KB per block to yield a CFI size of 1,000,000,000 (1 GB).

You can set the size of the CFI by specifying a maximum number of files to be space managed. Use the maxfiles option with the dsmmigfs update command. For example, if the file system block size is 1 KB and you specify maxfiles=1000, the CFI size is 1000 × 1 KB = 1 MB. In this example the CFI is only 1 MB, regardless of the total size of the file system. The value of the maxfiles option must be greater than or equal to the number of files in the file system.

.SpaceMan/reserved

When you add space management to a file system, the Tivoli® Storage Manager for Space Management client creates reserved files. The reserved files require 1 GB of space for each file system that is space managed.

The total space required can be estimated as 1 MB for base information plus 1 GB for reserved files for each space-managed file system. If hsmdisableautomigdaemons=no (the default value), you must also add space for the CFI.