I have two drives, one 512G (Samsung SSD) and one 500G (WD HDD). I created a new pool with a mirror vdev. During the pool creation, TrueNAS did recommend not to use different size drives, but I thought the delta is small and proceeded. At this point, the moirror is working fine excpet an “! mark” about “mixed disk capacity” appeared in the status. I searched the forum and saw lots of topic on pool/mirror related to different drive size but none related to my case directly.
Can someone kindly explain why I shouldn’t build a mirror with different size drives? I understand wasting drive space is one. Are there other complications I should be aware of?
All comments are appreciated. Thanks.
You are fine. The difference in size is very little.
Even if one of them is double the other, you will still be fine.
Both my boot pool and apps pool are mirrors of different size drives and no issue apart from the exclamation mark.