Data Domain: DD6400 does not expand file system properly following addition of new enclosures.

Summary: DD6400 is installed with 7.7.2 or 7.7.9. When creating a file system with the head unit alone, or head unit and one enclosure, then later adding any remaining enclosures, filesys expand will not expand to its fullest capacity. If all available storage in the enclosures is added and a file system is created from initial deployment, then there is no issue with capacity expansion. ...

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Symptoms

New shelves are added to the system. 
After running "filesys expand", the File system size is incorrect.

Cause

This behavior is due to an issue with Physical Extent Manager (PEM).
When an enclosure is added post FS creation, the PEM module fails to identify the next RAID array number to be created on newly added enclosure. It ends up expanding only existing arrays. It does not create new RAID arrays to meet the capacity.

Example:
In the example below, after running filesys expand, the active tier size should increase to 94.5 TiB. However, after the command is run, the new FS size is 56.6 TiB.
1) FS expansion on HU and with 1 ES40
  
Capacity licenses:
Feature Shelf Model Capacity Type State Expiration Date Note
------------------ --------------- ---------- --------------- ------ -----------
1 CAPACITY-ACTIVE PROTECTION_POOL 94.58 TiB permanent (int) active n/a
2 CLOUDTIER-CAPACITY n/a 181.89 TiB permanent (int) active n/a
------------------ --------------- ---------- --------------- ------ -----------
!!!! localhost YOUR DATA IS IN DANGER !!!! # ddsh -s disk show state
Tue May 3 18:07:46 PDT 2022
Enclosure Disk
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
--------- ----------------------------------------------
1 . . . . . . . . . . . .
2 v v v v v v v v v v v v v v v
--------- ----------------------------------------------
Legend State Count
------ --------------- -----
. In Use Disks 12
v Available Disks 15
------ --------------- -----
Total 27 disks
!!!! localhost YOUR DATA IS IN DANGER !!!! # ddsh -s filesys expand

!!!! localhost YOUR DATA IS IN DANGER !!!! ddsh -s disk show state; ddsh -s filesys show space; ddsh -s storage show all

Enclosure Disk
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
--------- ----------------------------------------------
1 . . . . . . . . . . . .
2 . . . . . . . . . . . . . . .
--------- ----------------------------------------------
Legend State Count
------ ------------ -----
. In Use Disks 27
------ ------------ -----
Total 27 disks
Active Tier:
Resource Size GiB Used GiB Avail GiB Use% Cleanable GiB
---------------- -------- -------- --------- ---- -------------
/data: pre-comp - 0.0 - - -
/data: post-comp 56911.7 0.1 56911.7 0% 0.0
/ddvar 78.6 4.6 70.0 6% -
/ddvar/core 251.9 0.1 239.0 0% -
---------------- -------- -------- --------- ---- -------------
The Active tier can be expanded by 37.92 TiB.
Active tier details:
Current active tier size: 56.6 TiB
Storage available to the active tier: 39.2 TiB
Active tier maximum capacity: 156.4 TiB
Cache tier details:
Current cache tier size: 3.2 TiB
Storage available to the cache tier: 0.0 TiB
Cloud tier details:
Current cloud tier metadata size: 21.7 TiB
Storage available to the cloud tier: 0.0 TiB
Shelf Capacity License:
License Model Total Used Remaining
--------------- --------------- -------- -------- ---------
CAPACITY-ACTIVE PROTECTION_POOL 94.5 TiB 56.3 TiB 38.1 TiB
--------------- --------------- -------- -------- ---------
The active tier size may be slightly larger than the licensed amount.


Resolution

Resolution:
This issue has been fixed in DDOS 7.7.3.0-1010549, DDOS-7.10.0.0 and later. 
The fix corrects the code error and correctly identifies the next RAID array number to be created on newly added enclosure drives.

Workaround: 
If you are planning to expand, upgrade to the fixed version, and then run expand.
If you are carrying out a partial expansion and you upgrade to a fixed release, the next FS expand will autocorrect the expanded size.

Affected Products

Data Domain, DD6400 Appliance
Article Properties
Article Number: 000210965
Article Type: Solution
Last Modified: 09 Oct 2024
Version:  6
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