I'm doing a large disk to disk rsync (running through the process of changing disk filesystem), and seeing slow write speed. ~4 to 10MB/s. Looking for some guidance on identifying what is causing such slow performance, and if it can be improved.

 

For the purpose of the long rsync task i switched "Tunable (md_write_method):" to "reconstruct write".

Please see diagnostics attached.

 

Cheers

tower-diagnostics-20180804-0904.zip

Edited August 7, 20187 yr by sketchy

Are you using -z with rsync? If yes don't, that enables compression and it's much slower for local or high bandwidth transfers.

Crikey you spotted that quickly! You're right, i am using -z, force of habit.

I have removed that option from the command and now see a massive improvement. The transfer is now showing high 20's to low 30's. Thank you @johnnie.black

 

Think i can squeeze any further improvement?

tower-diagnostics-20180804-0927.zip

It might fluctuate some depending on the file size, but with parity present and even with turbo write it won't go much faster than that, since one of the disks will do two simultaneous reads.

Understood! The healthy speed bump i have now will save me days. Thanks very much.