## Re-Initialize Space Efficient FB volumes 

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): 

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. 

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. 

## 12.3.6 Creating the volume groups 

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. 

## Determining whether an open system host is SCSI MAP256 or SCSI MASK 

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 . 

