I am currently transferring 500GB from unassigned drive (onboard SATA) directly to a disk of the array (also onboard SATA) via Krusader. Both disks are capable of doing 160-100MB/s and both parities can do 270-200MB/s (all numbers from recent pre-clear).

The files are mostly large (gigabytes) and should be sequentially written to the unassigned disk. It started transfer at 90MB/s and then slowed down to 45 within 15 minutes. There is nothing else using the disks and CPU is hoovering around 25% (not much else running).

 

After the noticed slow down, I started pre-clear on another drive (USB3.0) that should be able to do easily over 120MB/s (based on copying some files) but it is only doing it ~45-50MB/s. Am I getting penalized because of the dual parity or is something else going on?

 

CPU: i7 6700T

Mobo: Gigabyte G150-GSM with 5 out of 6 SATA ports in use + M.2 Cache (currently also in idle).

Edited March 13, 20224 yr by OrdinaryButt

https://wiki.unraid.net/Manual/Storage_Management#Array_Write_Modes

11 hours ago, trurl said:

https://wiki.unraid.net/Manual/Storage_Management#Array_Write_Modes

Thanks. I definitely missed the turbo mode option in the 2 months of learning and testing. However, that doesn't answer the subject line question - everything else identical, will dual parity be slower than single parity?

 

New question: Can I manually activate turbo mode when knowing a large data transfer will take place than de-activate it at the end?

1 minute ago, OrdinaryButt said:

New question: Can I manually activate turbo mode when knowing a large data transfer will take place than de-activate it at the end?

yes  You can do it at any time, even if a write is in progress

 

 

12 minutes ago, OrdinaryButt said:

everything else identical, will dual parity be slower than single parity?

Should be same speed (unless you happen to have a very slow CPU that struggles with the more complex parity calculation used for parity2).