On Fri, Oct 24, 2014 at 05:13:27AM +0000, Duncan wrote: > Zygo Blaxell posted on Thu, 23 Oct 2014 22:35:29 -0400 as excerpted: > > > My pet peeve: if balance is converting profiles from RAID1 to single, > > the conversion should be *instantaneous* (or at least small_constant * > > number_of_block_groups). Pick one mirror, keep all the chunks on that > > mirror, delete all the corresponding chunks on the other mirror. > > That would argue for either a third balance mode, --convert-only, or a > different tool, avoiding a rewrite of existing chunks entirely, simply > replicating them if adding redundancy or deleting a copy if reducing it, > as necessary.
Isn't that what soft does? [reading noises] OK, maybe not. 'soft' leaves a chunk alone if it already fits all the target profile requirements; however, in this case the profile (and only the profile, no data) is changing. I think just two modes are sufficient: one that does everything the most thorough way (throw scrub and defrag in there too, so we can do a single pass over the filesystem that does all the maintenance tasks at once), and one that takes advantage of every special-case shortcut available to achieve specific goals in the shortest time. I also think it's a little odd that conversion and balance are the same tool. Traditional RAID conversions don't care about filesystem layout, because they work on a completely separate layer (i.e. at the block level). It's certainly possible to perform a RAID conversion by reallocating all the filesystem-level objects, but just because you can doesn't mean you should. ;)
signature.asc
Description: Digital signature
