Data Domain: Unable to Create or Add a Disk to a Cache Tier in a Storage Pool

Summary: This article serves as reference on how to add disk to cache tier of a storage pool like DD6400

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Instructions

Creating cache tier (or adding a disk to an existing cache tier) on a storage pool mode like DD6400 will require a "force" attribute in the "storage add" command to complete cache volume creation.  With no "force" attribute in the "storage add" command, cache disk remains in "Available Disks (v)" state and no cache tier will be created as shown below.  
  
MMM DD HH:MM:SS <hostname> -ddsh: NOTICE: MSG-DDSH-00009: (tty=pts/0, session=4924, client_IP=XX.XX.XX.XX) sysadmin: command "storage add disks 1.3 tier cache" 

sysadmin@DD # disk show state
Enclosure   Disk
             1  2  3  4  5  6  7  8  9  10 11 12
---------   -------------------------------------
1            .  .  v  -  .  .  .  .  .  .  .  .
---------   -------------------------------------

Legend   State                 Count
------   -------------------   -----
.        In Use Disks          10
v        Available Disks       1
-        Not Installed Disks   1
------   -------------------   -----
Total 11 disks


sysadmin@DD # storage show all
Active tier details:

Current active tier size: 29.4 TiB
Storage available to the active tier: 5.4 TiB
Active tier maximum capacity: 156.4 TiB

Cache tier details:

Current cache tier size: 0.0 TiB          =====>>>  No Cache Tier Created 
Storage available to the cache tier: 1.6 TiB



Resolution:

If cache disk has been added with no "force" attribute and its state shows "Available Disks (v)", perform the following:
1. Connect to the Data Domain system over SSH using the sysadmin account.
2. Run the command: filesys expand

This creates the cache tier, which will now appear when using the storage show all command 
sysadmin@DD # disk show state
Enclosure   Disk                                 
             1  2  3  4  5  6  7  8  9  10 11 12 
---------   -------------------------------------
1            .  .  .  -  .  .  .  .  .  .  .  .  
---------   -------------------------------------
 
Legend   State                 Count
------   -------------------   -----
.        In Use Disks          11   
-        Not Installed Disks   1    
------   -------------------   -----
Total 11 disks


sysadmin@DD # storage show all
Active tier details:
 
Current active tier size: 29.4 TiB
Storage available to the active tier: 5.4 TiB
Active tier maximum capacity: 156.4 TiB
 
Cache tier details:
 
Current cache tier size: 1.6 TiB    =====>>>  Cache Tier Created 
Storage available to the cache tier: 0.0 TiB

Affected Products

DD6400 Appliance
Article Properties
Article Number: 000205814
Article Type: How To
Last Modified: 25 May 2023
Version:  3
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