Hey Hugo, thanks for the quick response.
On 09/02/2015 01:30 PM, Hugo Mills wrote: > You had some data on the first 8 drives with 6 data+2 parity, then > added four more. From that point on, you were adding block groups > with 10 data+2 parity. At some point, the first 8 drives became > full, and then new block groups have been added only to the new > drives, using 2 data+2 parity. Even though the old 8 drive RAID6 was not full yet? Read: There was still some terabytes of free space. >> Should I run btrfs balance on the filesystem? If so, what FILTERS >> would I then use in order for the data and therefore requests to >> be better distributed? > > Yes, you should run a balance. You probably need to free up some > space on the first 8 drives first, to give the allocator a chance > to use all 12 devices in a single stripe. This can also be done > with a balance. Sadly, with the striped RAID levels (0, 10, 5, 6), > it's generally harder to ensure that all of the data is striped as > evenly as is possible(*). I don't think there are any filters that > you should to use -- just balance everything. The first time > probably won't do the job fully. A second balance probably will. > These are going to take a very long time to run (in your case, I'd > guess at least a week for each balance). I would recommend starting > the balance in a tmux or screen session, and also creating a second > shell in the same session to run monitoring processes. I typically > use something like: > > watch -n60 sudo btrfs fi show\; echo\; btrfs fi df /mountpoint\; > echo\; btrfs bal stat /mountpoint Yeah, that's what I usually do. The thing is that one does not get any progress indication and estimate about how long a task will take. > (*) Hmmm... idea for a new filter: min/max stripe width? Then you > could balance only the block groups that aren't at full width, > which is probably what's needed here. Consider my question and motivation a rather obvious use case of running out of disk space (or iops) and simply adding some more drives. A balance needs to be straightforward for people to understand and perform such tasks. Regards Christian -- 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
