Data Domain: Adding External Storage while system Is Online

Applies to:

• All Data Domain systems supporting external storage
• All supported DDOS versions

Use-case:

• Expand storage capacity while keeping the filesystem online.
  • While this is possible, there is risk of downtime - for example: If SAS pathing is incorrectly cabled or mis-matched Firmware is present across Link Controllers (LCCs).

Adding external storage to a live system requires careful planning to avoid pathing issues and ensure that licensing is in place.

Before proceeding to add storage:

• Confirm hardware compatibility using the platform’s Hardware Guide.
  • Review the relevant PowerProtect and Data Domain Hardware Documentation Guide for supported configurations.
• Check for valid pathing and SAS-related issues using:

  • # enclosure show topology  
    # disk multipath status  
    # alerts show current

• Validate and install the required capacity licenses:
  • For ELMS Licensing:

    • # elicense show  
      # elicense update

  • For legacy licensing:

    • # license show  
      # license add Capacity-Active <license key>

Follow these steps to safely add external storage shelves, whilst keeping the system (and filesystem) online:

Preparation

1. Isolate work to only one SAS HBA path at a time.
2. Observe cable timing:
   • For 'ES' or 'FS' shelves (e.g.ES40 or FS240): Wait 2 minutes between cable actions.
   • For 'DS' shelves (e.g. DS60/DS600): Wait 8 minutes between cable actions.
3. Use free HBA slots if available.
4. Do not mix enclosure types on the same SAS path.
5. Do not exceed SAS chain limits.
6. Monitor the actions being undertaken using the command:

   • # log watch debug/platform/kern.info

7. Refer to 'Disk Shelf Guides' for cabling standards.

Installation Steps:

1. Rack the new enclosure. Do not connect SAS cables yet.
2. Power on both power supplies. Wait ~5 minutes for LCC initialization.
3. Cable shelves in this order:
   1. Connect inter-shelf cables first.
   2. Connect the host port to the head unit last.
   3. Wait the appropriate time between each cable action (see above).
4. Work on one SAS path at a time to maintain failover redundancy.

Verification:

Run the following commands to confirm the enclosure, SAS-multipath, and disks are as expected:

• • # enclosure show topology  
    # enclosure show summary  
    # disk port show summary  
    # disk show state

    • New disks should appear as "Unknown" or "Spare."
  • Two valid SAS paths must be active to EVERY enclosure.
    • See KB: Data Domain: SAS Cable Configuration, Topology checks, and Testing

Add Enclosure(s) to Tier:

• # storage add tier {active | archive | cache | cloud} enclosure <enclosure-id>

  • Example:

  • # storage add tier active enclosure 5

  • Controller (Head Unit) = enclosure-id 1
    First shelf = enclosure-id 2
    Second shelf = enclosure-id 3
• Disk state changes to "Available (v)"

Expand the Filesystem:

• # filesys expand

  • The 'Available' storage is appended to the usable capacity of the Filesystem

Post-Upgrade Checks:

• # storage show all  
  # filesys show space  
  # disk show state  
  # enclosure test topology <port> duration 1  
  # filesys status

Reference articles:

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Troubleshooting Adding a Shelf 
Data Domain: System Memory Requirements and Expanded Storage Configurations  

Additional information about licensing can be found in the relevant 'DDOS Admin Guide'.