Marc MERLIN posted on Sun, 04 May 2014 22:50:29 -0700 as excerpted: > In the second FS: >> >Label: btrfs_pool1 uuid: [...] >> > Total devices 1 FS bytes used 442.17GiB >> > devid 1 size 865.01GiB used 751.04GiB path [...] > > The difference is huge between 'Total used' and 'devid used'. > > Is btrfs going to fix this on its own, or likely not and I'm stuck doing > a full balance (without filters since I'm balancing data and not > metadata)? > > If that helps. > legolas:~# btrfs fi df /mnt/btrfs_pool1 > Data, single: total=734.01GiB, used=435.29GiB > System, DUP: total=8.00MiB, used=96.00KiB > System, single: total=4.00MiB, used=0.00 > Metadata, DUP: total=8.50GiB, used=6.74GiB > Metadata, single: total=8.00MiB, used=0.00
Definitely helps. The spread is in data. Try btrfs balance start -dusage=20 /mnt/btrfs_pool1 You still have plenty of unused (if allocated) space available, so you can play around with the usage= a bit. -dusage=20 will be faster than something like -dusage=50 or -dusage=80, likely MUCH faster, but will return less chunks to unallocated, as well. Still, your spread between data-total and data-used is high enough, I expect -dusage=20 will give you pretty good results. Since show says you still have ~100 GiB unallocated in df, there's no real urgency, and again I'd try -dusage=20 the first time. If that doesn't cut it you can of course try bumping the usage= as needed, but because you still have 100 GiB unallocated and because the data used vs. total spread is so big, I really do think -dusage=20 will do it for you. As your actual device usage goes up the spread between used and size will go down, meaning more frequent balances to keep some reasonable unallocated space available, and you'll either need to actually delete some stuff or to bump up those usage= numbers as well, but usage=20 is very likely to be sufficient at this point. I hadn't seen anyone try an actual formula as Brendan suggests in his post, and I'm not actually sure that formula will apply well in all use- cases as I think fragmentation and fill-pattern will have a lot to do with it, but based on his post it does apply for his use-case, and the same general principle if not the specific formula should apply everywhere and is what I'm doing above, only simply eyeballing it, not using a specific formula. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
