[Naac]

I asked this on another thread, but I don't understand why you would see real world difference between PCIe vs USB3.

When using this setup as a NAS, isn't your bottleneck the gigabit network from machine to machine? You'll saturate the 1 Gigabit link ( or even 2 Gigabit duplex ) before you can reach 5 Gigabits ( USB3 ) or 6 Gigabits ( PCIe )

[walterbell]

On a low-power CPU, overhead for USB protocol handling may be less efficient than PCIe DMA?

[pnutjam]

RAID seems very popular for 2 disk setups, but I don't like the cost benefit. With RAID under about 5 disks, you aren't getting much speedup, under 4 disks you can't do a proper fail-out and rebuild of a larger multi-disk volume.

I use 2 x 4TB disks in my homeserver, but I keep one online and have a script that brings up the other one periodically and rsyncs everything. This gives me a local backup, something RAID lacks, so I'm protected from fat fingering or accidentally deleting stuff. I also have very minimal downtime, because I can mount that drive in the place of the primary drive in just afew seconds.

I run xfs on the primary drive, and btrfs on the mirror, so I can take snapshots after I rsync and maintain differentials easily.

My point is, you should consider getting rid of RAID and just use the bare drive or LVS Volume.

[effie]

Agreed, RAID makes little sense if you want a quiet home storage that is used only occasionaly. Additional disk is better used for regular backups. If you need to minimize downtime and have the storage accessible 24/7, then RAID makes sense.

[foresto]

IIRC, SATA over USB3 can offer competitive performance for sequential I/O, but PCIe will give better random I/O performance and lower CPU usage.

tkaiser of the armbian project has a lot to say about this stuff. I find his posts in the cnx-software.com comments and armbian forums very helpful.

https://forum.armbian.com/topic/8097-nanopi-m4-performance-a...

https://github.com/ThomasKaiser/Knowledge

[mrb]

PCie 3 x1 is 8 gigabit/s. But yes you are right, the gigabit network should be the bottleneck either way.

[rbanffy]

For transfers, yes, but for housekeeping activities such as scrubbing, defragmenting, indexing, and deduplicating, not at all.