Parity, SAS or SATA?

[larson]

As in an earlier post, I am setting up  a new server, based on a decommissioned Proliant G10. Came with a full rack (4 bays of 4 3.5" SAS backplanes) stacked with HP 4 TB disks. All connected to the original HP Smart Array P816i-a SR Gen10. Obviously unconfiguring the array is enough to present disks in HBA mode for this card.

    

In addition I have some 8 TB disks, a Seagate SAS Enterprise Capacity ST8000NM0075 and a Seagate SATA Exos 7E10 ST8000NM017B-2TJ (and another similar SATA running as parity in my current system, to be migrated later). There seem to be a slight performance advantage for the SATA drive, it ran the preclear cycle in 31h52m compared to 35h41m for the SAS drive. My future plan is to run only SATA on one backplane, and keep SAS only on the other two.

 

In your opinion, which disk should I use as parity? Is there any advantage in using a SAS drive, that can counter the slower apparent speed compared to the SATA? Is it any advantage to keep the different kind of disks on separate backplanes?

 

Edited May 14 by larson

[JorgeB]

There shouldn't be any difference using SAS or SATA for parity, try to use your fastest sequential read/write drive, this is usually also the largest, just don't recommend SMR drives.