June 8, 20233 yr Hi, I am in the middle of transferring TBs of data to my new Unraid NAS. I have reconstrive write set and it seems to work. But every once in a while I discover spun down discs and slower write performance. It was my impression that when reconstructive write is enabled every write should spin up all disks. Any idea? Regards JP
June 8, 20233 yr Community Expert It won't change on its own unless you have the "turbo write" plugin installed, if it is and configured wrong it could flip it back to R/M/W.
June 8, 20233 yr Author I do but: That plugin also claims "reconstructive write" active. I set the number of disks to maximum (so it should never kick in and reduce it). And in order to make sure it does not fiddle with it I disabled it. The setting under Disk settings does still show md_write_method = reconstruct write and the plugin is disabled. Still believe me: After a while disks are spun down and I do see reads only from the spun up disks. Once I manually spin all disks up things are back to normal. VERY confusing.
June 8, 20233 yr Can't remember since which OS version, even you set reconstruct write, if multiple session write to array or file cross allocation to different disk, it will change to R/M/W and back. So you should review file allocation setting. Edited June 8, 20233 yr by Vr2Io
June 8, 20233 yr Community Expert Yes concurrent reads will trigger RMW and it can switch back and forth between both many times a second... but I've never seen that scenario causing drives to go to sleep, it should only happen when things are being quite hammered so they'd be needed... but maybe I just don't have enough drives to see that.
June 8, 20233 yr 22 minutes ago, Kilrah said: but I've never seen that scenario causing drives to go to sleep Agree. But may be some situation keeping in R-M-W long enough.... anyway haven't test or try to reproduce. Does OP use parity, reconstruct write only have meaning with parity. Just to be confirm, or provide screenshots / diagnostic. Edited June 8, 20233 yr by Vr2Io
June 9, 20233 yr Author 6 data disks plus 2 parity Currently 90-100 MB/sec constant writes (which is why I want reconstructive write to stay on). 🙂 I currently set "spin down" to never for the time being and keep filling up to drives. Will try to reproduce in 1-2 weeks and if I can reproduce it will send diagnostics here.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.