On 2020 Mai 20, Chris Murphy wrote: > On Wed, May 20, 2020 at 3:02 PM Johannes Hirte > <johannes.hirte@xxxxxxxxxxxxx> wrote: > > > > On 2020 Mai 19, Zygo Blaxell wrote: > > > > > > Corollary: Never use space_cache=v1 with raid5 or raid6 data. > > > space_cache=v1 puts some metadata (free space cache) in data block > > > groups, so it violates the "never use raid5 or raid6 for metadata" rule. > > > space_cache=v2 eliminates this problem by storing the free space tree > > > in metadata block groups. > > > > > > > This should not be a real problem, as the space-cache can be discarded > > and rebuild anytime. Or do I miss something? > > The bitmap locations for the free space cache are referred to in the > extent tree. It's not as trivial update or drop the v1 space cache as > it is the v2 which is in its own btree. I still don't see the problem. Free space cache is needed for performance, not function. If it's not available, this can be ignored. -- Regards, Johannes Hirte
