So, for a while now I've been recommending small filtered balances to
people as part of regular maintenance for BTRFS filesystems under the
logic that it does help in some cases and can't really hurt (and if done
right, is really inexpensive in terms of resources). This ended up
integrated partially in the info text next to the BTRFS charts on
netdata's dashboard, and someone has now pointed out (correctly I might
add) that this is at odds with the BTRFS FAQ entry on balances.
For reference, here's the bit about it in netdata:
You can keep your volume healthy by running the `btrfs balance` command
on it regularly (check `man btrfs-balance` for more info).
And here's the FAQ entry:
Q: Do I need to run a balance regularly?
A: In general usage, no. A full unfiltered balance typically takes a
long time, and will rewrite huge amounts of data unnecessarily. You may
wish to run a balance on metadata only (see Balance_Filters) if you find
you have very large amounts of metadata space allocated but unused, but
this should be a last resort.
I've commented in the issue in netdata's issue tracker that I feel that
the FAQ entry could be better worded (strictly speaking, you don't
_need_ to run balances regularly, but it's usually a good idea).
Looking at both though, I think they could probably both be improved,
but I would like to get some input here on what people actually think
the best current practices are regarding this (and ideally why they feel
that way) before I go and change anything.
So, on that note, how does anybody else out there feel about this? Is
balancing regularly with filters restricting things to small numbers of
mostly empty chunks a good thing for regular maintenance or not?
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