On Thu, May 09, 2013 at 03:41:49PM -0500, Kyle Gates wrote: > I'll preface that I'm running Ubuntu 13.04 with the standard 3.8 > series kernel so please disregard if this has been fixed in higher > versions. This is on a btrfs RAID1 with 3 then 4 disks. > > My use case is to set the nocow 'C' flag on a directory and copy in > some files, then make lots of writes (same file sizes) and note that > the number of extents stays the same, good. > Then run a balance (I added a disk) and start making writes again, > now the number of extents starts climbing, boo. > Is this standard behavior? I realize a balance will cow the files. > Are they also being checksummed thereby breaking the nocow flag? > > I have made no snapshots and made no writes to said files while the > balance was running.
Hi Kyle, It's hard to say if it's standard, it is a side effect casued by balance. During balance, our reloc root works like a snapshot, so we set last_snapshot on the fs root, and this makes new nocow writes think that we have to do cow as the extent is created before taking snapshot. But the nocow 'C' flag on the file is still there, if you make new writes on the new extent after balance, you still get the same number of extents. thanks, liubo -- 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
