On 8/10/18 6:42 PM, Dan Merillat wrote: > On Fri, Aug 10, 2018 at 6:05 AM, Qu Wenruo <quwenruo.bt...@gmx.com> wrote: > >> >> Although not sure about the details, but the fs looks pretty huge. >> Tons of subvolume and its free space cache inodes. > > 11TB, 3 or so subvolumes and two snapshots I think. Not particularly > large for NAS. > >> But only 3 tree reloc trees, unless you have tons of reflinked files >> (off-line deduped), it shouldn't cause a lot of problem. > > There's going to be a ton of reflinked files. Both cp --reflink and > via the wholefile dedup. > > I freed up ~1/2 TB last month doing dedup. > >> At least, we have some progress dropping tree reloc tree for subvolume 6482. > > Is there a way to get an idea of how much work is left to be done on > the reloc tree?
You could inspect by the level. But each level change is a huge step forward. > Can I walk it > with btrfs-inspect? Of course you can. Using -b <bytenr> could show the remaining tree. > > dump-tree -t TREE_RELOC is quite enormous (13+ million lines before I gave up) No wonder, since it's kind of snapshot of your subvolume. > >> If you check the dump-tree output for the following data, the "drop key" >> should change during mount: (inspect dump-tree can be run mounted) >> item 175 key (TREE_RELOC ROOT_ITEM 6482) itemoff 8271 itemsize 439 >> <snip> >> drop key (2769795 EXTENT_DATA 12665933824) level 2 >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> >> So for the worst case scenario, there is some way to determine whether >> it's processing. > > I'll keep an eye on that. > >> And according to the level (3), which is not small for each subvolume, I >> doubt that's the reason why it's so slow. >> >> BTW, for last skip_balance mount, is there any kernel message like >> "balance: resume skipped"? > > No, the only reference to balance in kern.log is a hung > btrfs_cancel_balance from the first reboot. That's strange. But considering your amount of block groups, mount itself may take some time (before trying to resume balance). Thanks, Qu > >> Have you tried mount the fs readonly with skip_balance? And then remount >> rw, still with skip_balance? > > No, every operation takes a long time. It's still running the btrfs > check, although I'm > going to cancel it and try mount -o ro,skip_balance before I go to > sleep and see where it is tomorrow. > > Thank you for taking the time to help me with this. >
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