I have 2 questions about stacking with the sg500x switch. We have 3 of them.
question #1 - can we LAG two stacking ports together, to increase the stack bandwidth to 20gbps? I'd like the increased bandwidth, and you can LAG the regular 10G ports together but the manual and the admin UI doesn't appear to support two stacking connections between two switches.
question #2 - the manual indicates that you can configure all 4 10G ports as regular or stacking ports as needed. However, after digging a bit it appears this may be an error in the documentation. Elsewhere in the documentation it mentions that by setting the stack configuration to "standalone" the 2 stacking ports will automatically be reclaimed as standard non-stacking ports. So that explains how to get all 4 configured as regular ports, but how do I configure all 4 ports as stacking ports? Of course, this doesn't matter with my configuration if I can't LAG two stacking ports together. My hope was to have 2 10G ports to each switch from each of the other 2 switches. Like this:
switch A S1 & S2 <-> switch B S1 & S2
switch A S3 & S4 <-> switch C S1 & S2
switch B S3 & S4 <-> switch C S3 & S4
1- Unfortunately you can not LAG the stacking ports. The other port will shut down and act as a backup.
2- I will double check the documentation on this one, however, I can tell you that only one set of 10G ports can be used as stack ports. As you mentioned, in standalone, you can reclaim them for regular use.
Might I offer as a suggestion- If you are really set on getting the 20G link, you could set all the switches to standalone and use several LAGs between them. This would add additional work as each switch must now be configured individually, but it would allow you to complete your design.