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Date: Mon, 5 Jul 2004 13:51:00 -0700 (PDT)
From: Joe Schmoe <non_secure@yahoo.com>
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Subject: concurrent scp transfers (and a testing methodology ?)
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I have read several documents on the number of
concurrent  https sessions a FreeBSD system is capable
of.

However, I wonder how well this relates to how many
ssh sessions (scp file transfers, specifically) that a
FreeBSD server can handle.  Can anyone throw out some
basic numbers for this ?  Assuming a 1ghz p3 and 2gigs
of RAM, and assuming that everyone is transferring a
totally different file.  (so there is no amount of
cache hits - everything comes straight off the drives)

I would think the major bottleneck would be disk - you
would start chugging the disks far before you used up
all the CPU on a 1ghz p3 ... but what is the second
bottleneck ?  Is it cpu, or is it ram (or mbufs, etc.)

Would it be a reasonable test to just start up scp
sessions from the machine to itself and then divide
the number of sessions you can acceptably create by
the number 2 ?  Or is this somehow a flawed test ?

Any additional comments (kernel tunes, settings, war
stories) are greatly appreciated. (like, does SMP help
a lot here, or just a little ?)


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