February 17, 20242 yr I recently tried to add two new SSD to my cache pool and are experiencing an unexpected behavior. The cache pool had one 500GB SSD (SATA) with BTRFS RAID1. I assumed I can add my two new drives (also 500GB, but NVME) to the pool, so that the original SSD will be mirrored to the two new ones. However, now I see a pool size of 750GB instead of 500GB. In addition, it displays 381GB in use and 228 as free, which are just over 600GB. So now I am a bit confused about what's going on. All I could find is, that if disk size is the same, it should be possible to just add the new drives and it should mirror to the new drives. Can somebody explain or point me in the right direction? Thanks! If any info is missing, please let me know! I am now on v6.12.8. However, when I added the two new drives, I was still on 6.9.2. Just updated today, after I had problems a while ago and had to roll back and forgot to try again. Just in case this could be relevant. --- Another question: Once this is cleared up and the cache pool works as intended with 500GB pool size - can I just remove the original drive from the pool and only leave the two new ones? Or will that cause problems? Edited February 17, 20242 yr by Junsas
February 18, 20242 yr Community Expert 14 hours ago, Junsas said: However, now I see a pool size of 750GB instead of 500GB. This is correct, 3 x 500GB with btrfs raid1 will result in 750GB usable, if you want to create a 3 way mirror instead you need to convert to raid1c3, then you'll get 500GB pool size. 14 hours ago, Junsas said: it displays 381GB in use and 228 as free, which are just over 600GB. This is a btrfs issue when used with an odd number of devices, used space will be correct, free space will get closer to correct as the pool is filled up.
February 19, 20242 yr Author Ok thanks for the quick reply! I thought raid 1 would mirror also with more than 2 drives. Regarding my 2nd question: I only want the two new drives in the pool. Can I just remove the original one and the pool will be OK with the 2 remaining drives? Or is it more complicated than that? EDIT: Ok, this sounds like it will be possible: Edited February 19, 20242 yr by Junsas
February 19, 20242 yr Community Expert 9 minutes ago, Junsas said: Can I just remove the original one and the pool will be OK with the 2 remaining drives? Or is it more complicated than that? You can, take a look here: https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=480418
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.