8456ch_DSCLI.fm Draft Document for Review December 5, 2019 4:33 pm Re-Initialize Space Efficient FB volumes 12.3.6 Creating the volume groups Determining whether an open system host is SCSI MAP256 or  SCSI MASK 402  IBM DS8900F Architecture and Implementation Users can use the  initfbvol  command to reinitialize online Space Efficient FB volumes. The command includes options to prevent the accidental reinitialization of volumes that are in  use. An FB volume is considered to be in use if it is participating in a Copy Services  relationship or if the volume received any I/O operation in the previous five minutes. All data  will be lost when this command is used. Volume reinitialization is controlled by the  -action releasespace  and  -force  parameters in  the following manner (Example 12-44): FB volumes are assigned to open system hosts by using volume groups. Do not confuse  them with the  volume groups  term, which is used in AIX. A fixed-block volume can be a  member of multiple volume groups. Volumes can be added or removed from volume groups  as required. Each volume group must be SCSI MAP256 or SCSI MASK, depending on the  SCSI LUN address discovery method that is used by the operating system to which the  volume group is attached. Note:  There are two ways to create volume groups and map the volumes to the hosts.  Volume groups can be created manually in single steps or automatically. Automatically is  done together with the  mkhost and  chhost  command and is nowadays the recommended  method for mapping volumes to host systems. Mapping of volumes to hosts or host groups is also called storage partitioning. The following sections describes both ways but understand that the manual way is only there  for backward compatibility and needs to applied with care to make sure that all needed steps  are done to fully reflect the results and views in the DS GUI. First, determine the type of SCSI host with which you are working. Then, use the  lshosttype command with the  -type  parameter of  scsimask  and then  scsimap256 .  dscli>  initfbvol -action releasespace -force 2005 CMUC00337W initfbvol: Are you sure that you want to free all extents and lose the  data associated with the FB volume 2005? [Y/N]:y CMUC00340I initfbvol: 2005: The command releasespace has completed successfully. Example 12-44 Using the initfbvol command to reinitialize a volume GLYPH<SM590000> The  releasespace  parameter is used to free up all extents/tracks associated with the  specified volume so they can then be reused by other Space Efficient volumes. GLYPH<SM590000> The  -force  parameter is required in order for the  initfbvol  command to reinitialize the  specified volume if it is in use. GLYPH<SM590000> When both of these parameters are used, the user is prompted with a Y/N response in  order for the command to proceed with the reinitialization process.