Misreported Size RAIDz1 Expansion
Description
Problem/Justification
Impact
Activity
Bug Clerk March 3, 2025 at 9:31 PM
This issue has now been closed. Comments made after this point may not be viewed by the TrueNAS Teams. Please open a new issue if you have found a problem or need to re-engage with the TrueNAS Engineering Teams.
Bug Clerk March 3, 2025 at 9:31 PM
This does not appear to be an error in TrueNAS code or regression in functionality. The community forums are available to assist: https://forums.truenas.com/.
Bug Clerk March 2, 2025 at 5:45 PM
Thank you for submitting this TrueNAS Bug Report! So that we can quickly investigate your issue, please attach a Debug file and any other information related to this issue through our secure and private upload service below. Debug files can be generated in the UI by navigating to System -> Advanced -> Save Debug.
https://ixsystems.atlassian.net/servicedesk/customer/portal/15/group/37/create/153
Details
Details
Assignee
Reporter
Fix versions
Affects versions
Priority

I've recently switch to TrueNAS because support for RAIDz expansion was added however I've noticed a discrepancy with the reported capacity in the UI since undergoing an expansion - to get data into TrueNAS I went through the following configurations for various unimportant reasons (in TB), rebuilding and resilvering each time:
4, 4, 10
4, 4, 10, 12
4, 4, 10, 14
4, 10, 14, 14
10, 14, 14, 14
14, 14, 14, 14
After this I would have expected a reported usable capacity of around the ~40TB mark (maybe a little less because of the few loses I'm aware of with expansion).
However the reported usable capacity is 33.79TB.
Interestingly `zpool list` shows information far closer to what I'd actually expect so I'm not sure where the misreporting is coming from or if the reporting in the UI can be trusted.
Session ID: ae1735fa-1b3d-6216-4628-0dd427db266c