Which gigabit netgear switch is best for jumboframes ?

NilsG wrote:
I will of course get higher transfer rates with direct NAS -> PC transfer !

You may be right, though it is not obvious. Even smaller switches are often capable of wire-speed performance - in which case the switch will not degrade performance at all.

NilsG wrote:
The whole house are using high quality cat7 ethernet cables

I believe that "cat 7" is not official. You might have class F or class FA (spec'd for 10 gig ethernet). Maintaining this performance also requires care in wiring up the connectors in the faceplates, and of course any patch cables. So even if the cable itself is good, you might still have end-to-end issues. Does the NAS report any packet loss? (TCP retransmissions, etc).

NilsG wrote:
turning off jumboframes in my pc gives severerly lower transferrate with big files - but almost no difference in transfer of small files ?

That is believable. Jumbo frames generally help because they reduce the interupts per second processing load on the PC. They actually don't improve the network itself. Often the advanced settings on the NIC can be used to improve the non-Jumbo frame performance.

BTW, small file transfers often end up bottlenecked on the NAS. Sequential read/writes are quite fast (writes generally slower with RAID-5 or Raid-6, since the parity blocks also need to be re-written). Copying lots of small files (or updating databases) creates more seeking on the NAS drives, which will slow them down. This is one reason why enterprise storage systems are spec'd in IOs per second, and not MB/s,

NilsG wrote:
My "concern" is of course the variable speed in upload - and I can't think of anything else than that it must be the switch/es that causes it My main computer and the nas are on the same switch - just copying files of different sizes (nas - pc - nas) with a horrible low speed at merely 20Mbps

Trying a direct connect might confirm (or refute) this theory.

Note that most good switches maintain full bandwidth between the ports (e.g, an 8 port gigabit switch would have a 16 gigabit internal bandwidth so it wouldn't slow down when multiple links are active). The connections between your GS108s are of course limited to 1 gbit. So if the switches are co-located you can get higher overall throughput if you consolidate them with a bigger switch. This only matters if you have multiple users loading the links between the switches.

NilsG wrote:
EDIT; I think I'll order a Intel Pro/1000MT Dual Port Adapter and connect this pc and the nas directly since the Ultra6 have two nics - that should do it ?

Just connecting two ethernet cables won't help, unless you also can set up teaming. That requires a managed switch. If you are thinking about dual-homing, then that requires some special care on the network configuration. I strongly recommend that you at least test direct-connect before simply throwing more hardware at the problem.