On Mon, Dec 23, 2019 at 02:44:07PM +0100, Stéphane Lesimple wrote: > Hello btrfs gurus, > > Has this ever been considered to implement a feature so that metadata chunks > would always be allocated on a given set of disks part of the btrfs > filesystem? Yes, many times. There was even an RFC implementation, many years ago, but it wasn't merged. Hugo. > As metadata use can be intensive and some operations are known to be slow > (such as backref walking), I'm under the (maybe wrong) impression that > having a set of small ssd's just for the metadata would give quite a boost > to a filesystem. Maybe even make qgroups more usable with volumes having 10 > snapshots? > > This could just be a preference set on the allocator, so that a 6 disks > raid1 FS with 4 spinning disks and 2 ssds prefer to allocate metadata on the > ssd than on the slow drives (and falling back to spinning disks if ssds are > full, with the possibility to rebalance later). > > Would such a feature make sense? > -- Hugo Mills | Quantum Mechanics: the dreams stuff is made of. hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 |
