8.1 Preventing migration of the .SPACEMAN and metadata  directories 8.2 Maximizing migration performance with redundant copies This section describes an IBM Spectrum Scale policy rule that you should have in place to  help ensure the correct operation of your IBM Spectrum Archive EE system. You can prevent migration of the  .SPACEMAN  directory and the IBM Spectrum Archive EE  metadata directory of a GPFS file system by excluding these directories by having an IBM  Spectrum Scale policy rule in place. Example 8-1 shows how an  exclude  statement can look  in an IBM Spectrum Scale migration policy file where the metadata directory starts with the  text “ /ibm/glues/.ltfsee ”. For more information and detailed examples, see 7.10.2, “Threshold-based migration” on  page 161 and 7.10.3, “Manual migration” on page 166. To minimize drive mounts/unmounts and to maximize performance with multiple copies, set  the mount limit per tape cartridge pool to equal the number of tape drives in the node group  divided by the number of copies. The mount limit attribute of a tape cartridge pool specifies  the maximum allocated number of drives that are used for migration for the tape cartridge  pool. A value of 0 means no limit and is also the default value. For example, if there are four drives and two copies initially, set the mount limit to 2 for the  primary tape cartridge pool and 2 for the copy tape cartridge pool. These settings maximize  the migration performance because both the primary and copy jobs are run in parallel by  using two tape drives each for each tape cartridge pool. This action also avoids unnecessary  mounts/unmounts of tape cartridges.  To show the current mount limit setting for a tape cartridge pool, run the following command: ltfsee pool show -p <poolname> [-l <libraryname>] To set the mount limit setting for a tape cartridge pool, run the following command: ltfsee pool set -p <poolname> [-l <libraryname>] -a <attribute> -v <value> Example 8-1 IBM Spectrum Scale sample directory exclude statement in the migration policy file define( user_exclude_list, ( PATH_NAME LIKE '/ibm/glues/.ltfsee/%' OR PATH_NAME LIKE '%/.SpaceMan/%' OR PATH_NAME LIKE '%/.snapshots/%' ) ) Chapter 8. Hints, tips, and preferred practices  227