On 4/30/20 23:05, Alexandru Dordea wrote: > Don’t get me wrong, the single 100% CPU is only during balance process. > By running "btrfs device delete missing /storage”there is no impact on CPU/RAM. I do have 64GB DDR4 ECC but there is no more of 3GB ram usage. 3GB used for what, does that include the system buffer cache? > > I can see that @Chris Murphy mention that disabling the cache will impact performance. Did you tried that? > On my devices I do have cache enabled and till now this is the only thing that I didn't tried :) It didn't seem to make an obvious difference, which surprised me a little since the I/O seems so random. Maybe btrfs is already sticking a lot of fences (barriers) into the write stream so the drive can't do much reordering anyway? I've always left write caching enabled in my drives since my system is plugged into reliable power. I assume the only reason to turn it off is to reduce the chance of filesystem corruption in case I have to force the machine to reboot while the operation is still going. Down to only 1.99 TB now! Wow! --Phil
