GLYPH<SM590000> Always cross-check the host LUN ID information with the vdisk_UID of the SAN Volume  Controller. Do not assume that the operating system recognizes, creates, and numbers  the disk devices in the same sequence or with the same numbers as you created them in  the SAN Volume Controller/Storwize. GLYPH<SM590000> Ensure that you delete any volume or LUN definition in the server  before  you unmap it in  IBM Spectrum Virtualize. For example, in AIX, remove the hdisk from the volume group  ( reducevg ) and delete the associated hdisk device ( rmdev ). GLYPH<SM590000> From version 7.4 onwards, consider enabling volume protection by using  chsystem  -vdiskprotectionenabled yes -vdiskprotectiontime <value_in_minutes> . Volume  protection ensures that some CLI actions (most of those that either explicitly or implicitly  remove host-volume mappings or delete volumes) are policed to prevent the removal of  mappings to volumes or deletion of volumes that are considered  active  (the system has  detected I/O activity within the specified time in minutes to the volume from any host). GLYPH<SM590000> Ensure that you explicitly remove a volume from any volume-to-host mappings and any  copy services relationship to which it belongs  before  you delete it.  GLYPH<SM590000> When you are deallocating volumes, plan for an interval between unmapping them to  hosts ( rmvdiskhostmap ) and deleting them ( rmvdisk ). The IBM internal Storage Technical  Quality Review Process (STQRP) asks for a minimum of a 48-hour period, and having at  least a one business day interval so that you can perform a quick backout if you later  realize you still need some data on that volume. GLYPH<SM590000> Before you map new servers to IBM Spectrum Virtualize, verify that they are all error free.  Fix any errors that you find in your server and IBM Spectrum Virtualize before you  proceed. In IBM Spectrum Virtualize, pay special attention to anything inactive in the  svcinfo lsfabric  command. GLYPH<SM590000> Plan for an interval between updating the zoning in each of your redundant SAN fabrics,  such as at least 30 minutes. This interval allows for failover to occur and stabilize, and for  you to be notified if unexpected errors occur. GLYPH<SM590000> After you perform the SAN zoning from one server’s HBA to IBM Spectrum Virtualize, you  should list its WWPN by using the  svcinfo lshbaportcandidate  command. Use the  svcinfo lsfabric  command to certify that it was detected by the IBM Spectrum Virtualize  nodes and ports that you expected. When you create the host definition in IBM Spectrum  Virtualize ( svctask mkhost ), try to avoid the  -force  parameter. If you do not see the host’s  WWPNs, it might be necessary to scan fabric from the host. For example, use the  cfgmgr command in AIX. 406  IBM System Storage SAN Volume Controller, IBM Storwize V7000, and IBM FlashSystem 7200 Best  When you add and remove a host (or hosts) in IBM Spectrum Virtualize, consider the  following guidelines: If you issue the  svctask rmvdisk  command and it still has pending mappings, IBM  Spectrum Virtualize prompts you to confirm and is a hint that you might have done  something incorrectly. Attention:  You must avoid the use of the  -force  parameter in  rmvdisk . Note:  Volume protection cannot be overridden by the use of the  -force  flag in the  affected CLI commands. Volume protection must be disabled to carry on an activity that  is currently blocked. 9.3.2 Adding and removing hosts