Maximum number of concurrent users logged on via telnet or ssh? I have read that the kernel by default only allocates 256 TTY's... so you could theoretically have 256 sessions going at one time depending on your RAM. The nice thing about Linux is, of course, that you can recompile the kernel to adust this number higher or lower.
As far as simultaneous network connections to things such as Samba, NFS, etc, the only limitation is hardware. There is no hard-coded licensing limit as Microsoft has in some of their products.
Not sure if that's what you're getting at... a search on groups.google.com may glean a bit more useful information for you.
Well, since you said IIS I'm assuming you are talking HTTP requests rather than TTY sessions. There is a fair bit of data available on the internet that shows that a Linux/Apache combination can sustain many more concurrent http requests than a IIS/NT set up, all things being equal (many of these comparative studies are fairly dated though).
It's probably still true, but with memory prices at all time lows, (NT tended to be a lousy memory manager, XP, 2000 are better but like lot's of memory just the same) it matters less.
I'd double check that comment that "IIS out of the box can only handle 10 concurrent users ", and lastly be careful writing papers like that in an IIS shop, you may find yourself gnawing at your leg to get out of the trap you're in :)
There is a fair bit of data available on the internet that shows that a Linux/Apache combination can sustain many more concurrent http requests than a IIS/NT set up
I am talking http requests. I have found some reports but usually the reports are biased one way or the other. I'm juts looking for a simple answer wchich is really not in any of the reports I have found.
There are a number of papers at the MS site which talk about this. I have verified myself that "IIS out of the box can only handle 10 concurrent users". When you have 10 requests that take a bit longer, say going against a database, any further requests are saved in queue. As the 10 requests are completed the number of requests in the queue do down. This setting can be changed within the registry.
Maybe "concurrent users" not quite the right term. Perhaps it should be called "concurrent threads" or "concurrent active users".
The point of my research is not to bash IIS or *nix. It's just part of a program to educate about stress/performance testing and to dispell myths about the two systems. Believe me IIS can blaze through normal html files and simple ASP stuff even if there are only 10 active threads.
We have many Unix boxes but mostly for Lotus Notes and DB stuff.