June 6, 20179 yr I have two Cache drives which i added in it selected btrfs by default. One is a 128GB SSD the other is a 256GB SSD. It made a volume of 176GB but my programs are saying no space left when i try to write to the cache. it is also saying 41GB is used and 70GB is free which is 111GB total which is wrong. My docker allocations writing to a cache only share are reporting only 60GB free at the moment. Filesystem Size Used Avail Use% Mounted on /dev/sdm1 176G 41G 70G 37% /mnt/cache
June 6, 20179 yr 176GB is wrong, you can only have at most 128GB total space with RAID1 on your two drives because each bit has to have a copy on the other drive. This is a known issue, not really controlled by unraid, it's the BTRFS free space reporting that has the issue.
June 6, 20179 yr Community Expert It is a known BTRFS issue that with drives of mixed sizes the space reported is incorrect. With 2 devices the available space is limited to that of the smaller device.
June 6, 20179 yr 9 hours ago, Maticks said: so i should pull out the 128GB drive to get 256GB free if i need to. Or add another 128 to get 256 with redundancy.
June 6, 20179 yr Community Expert 11 hours ago, itimpi said: It is a known BTRFS issue that with drives of mixed sizes the space reported is incorrect The correct answer for different configurations can be calculated here: btrfs disk usage calculator And the way to get different cache pool configurations in unRAID and other info about cache pools is in the FAQ here:
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