stelks Posted February 14, 2021 Share Posted February 14, 2021 I added a second drive (256GB) to my 512GB cache pool, instantly it started to do a btrfs balance. When this started there was ONLY 200ish GB of data in the pool. At first it looked right and was showing 750GB total space, but once it was done it only has 1GB free and it shows it only has a total of 537GB not 750GB of space. I have restarted my server, ran a btrfs scrub and tried to balance again. Any ideas how to fix? Quote Link to comment
itimpi Posted February 14, 2021 Share Posted February 14, 2021 The default profile is the btrfs version of raid1. With mixed drive sizes this makes the available disk space equivalent to the smaller drive. If you want the space to be additive then you need to switch the profile to be Single. 1 Quote Link to comment
stelks Posted February 14, 2021 Author Share Posted February 14, 2021 (edited) 18 minutes ago, itimpi said: The default profile is the btrfs version of raid1. With mixed drive sizes this makes the available disk space equivalent to the smaller drive. If you want the space to be additive then you need to switch the profile to be Single. Thanks for the response. I have a couple questions though if you could help. If the space is limited to twice the size of the smallest drive it should be (256x2) which is 512, but in the screenshot it shows about 537GB of space. Secondly it is showing in the screenshot that the size is 756GB, is it normal for that to not reflect the actual size based on btrfs profile? I have looked around to try and find what profile the pool is in but have not found anything, do I need to turn off my array to change that? EDIT: Just found the "convert to single mode" button under that balance settings. Ill give that a go. Edited February 14, 2021 by stelks Quote Link to comment
JonathanM Posted February 14, 2021 Share Posted February 14, 2021 16 minutes ago, stelks said: If the space is limited to twice the size of the smallest drive No, with 2 drives in RAID1, the space is limited to just the size of the smallest drive, not 2x. RAID1 means a copy of the data must exist on 2 separate volumes. Quote Link to comment
stelks Posted February 14, 2021 Author Share Posted February 14, 2021 Just now, jonathanm said: No, with 2 drives in RAID1, the space is limited to just the size of the smallest drive, not 2x. RAID1 means a copy of the data must exist on 2 separate volumes. Got it so the reason it looked like their was so much more data on the drive is it replicated the data on each drive and counted it. Thanks. Quote Link to comment
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