mrgstiffler Posted January 13, 2019 Share Posted January 13, 2019 (edited) I added a third SSD to my cache and set the balance to -dconvert=raid5 -mconvert=raid1. It ran the balance and finished just fine. It's showing 1.5TB free instead of the 1TB I would expect from RAID5. Is this just a display error or is it actually going to try and fail to use that space? Edited January 14, 2019 by mrgstiffler Quote Link to comment
JorgeB Posted January 13, 2019 Share Posted January 13, 2019 It's a btrfs limitation with raid5/6, used spaced will show correctly, available space will not account for parity, but since it still decreases with used space not much of a problem, also note that while you can use raid5/6, I use it myself, it's still less stable than other profiles, and a UPS is strongly recommended because of the the write hole issue that affects most raid5/6 implementations. 1 Quote Link to comment
mrgstiffler Posted January 14, 2019 Author Share Posted January 14, 2019 That makes sense. Thanks. Quote Link to comment
MWDK Posted January 2, 2020 Share Posted January 2, 2020 So basically a 3 or 4 disc RAID5 cache tells you some wrong numbers but it works 100% correctly? I am about to install 4 x 240gb ssd's as cache - or atleast that was the thought I have 1 x 512GB PCIe NVME as cache right now and 1 x 256GB M.2 unassigned that im not sure how to use best way Quote Link to comment
JorgeB Posted January 2, 2020 Share Posted January 2, 2020 Free space is incorrectly reported, also note that btrfs raid5/6 still has some issues. Quote Link to comment
MWDK Posted January 2, 2020 Share Posted January 2, 2020 10 hours ago, johnnie.black said: Free space is incorrectly reported, also note that btrfs raid5/6 still has some issues. So what setting to be bulletproof? Quote Link to comment
JorgeB Posted January 2, 2020 Share Posted January 2, 2020 9 minutes ago, MWDK said: So what setting to be bulletproof? Nothing is bulletproof, btrfs raid1/0/10 is more stable then raid5/6, but I've been using several raid5 pools for some time now without issues, just make sure any important data is regularly backed up, as it should always be. Quote Link to comment
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