Hi, Our OS10 for these switches does not support stacking, so you can use the older OS 9 or use a third party OS. You can get OS 9 here [URL]   Cumulus Linux OS  Big Switch Networks Switch Light OS  Pluribus OS   Are the third party OS options.
Hello, I bought two used S6010-on switches to play with. They didn't come with an OS installed though just ONIE. What OS should I run so I can stack them. Do I need Dell Networking OS? If so where can I find/buy/download it? Thanks.  
S6010-on operating system