On 23 November 2014 at 08:52, Duncan <1i5t5.dun...@cox.net> wrote: > [a whole lot]
Thanks for the long post, Duncan. My venture into the finer details of balance began with converting an ext4 fs to btrfs and after an inital defrag having a full balance fail with about a third to go. Consecutive full balances further reduced the number of chunks and got me closer to finish without the infamous ENOSPC. After 3-4 full balance runs it failed with less than 8% to go. The balance run now finishes without errors with usage=99 and I think I'll leave it at that. No RAID yet but will convert to RAID1. Is it correct that there is no reason to ever do a 100% balance as routine maintenance? I mean if you really need that last 1% space you actually need a disk upgrade instead. How about running a monthly maintenance job that uses bytes_used and dev_item.bytes_used from btrfs-show-super to approximate the balance need? (dev_item.bytes_used - bytes_used) / bytes_used == extra device space used The extra device space used after my balance usage=99 is 0,15%. It was 7,0% before I began tinkering with usage and ran into ENOSPC and I think it is safe to assume that it was a lot more right after the fs conversion. So lets iterate a balance run which begins with usage=0 and increases in steps of 5 or 10 and stops at 90 or 99 or when the extra device space used is less than 1%. Does it make sense? -- 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
