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From: Rashid Karimov <rashid@rk.ios.com>
Message-Id: <199511182321.SAA27795@rk.ios.com>
Subject: Re: MAXUSERS=64 -- kernel panics
To: jimd@mistery.mcafee.com (Jim Dennis)
Date: Sat, 18 Nov 1995 18:21:55 -0500 (EST)
Cc: questions@freebsd.org
In-Reply-To: <199511180135.RAA07661@mistery.mcafee.com> from "Jim Dennis" at Nov 17, 95 05:35:55 pm
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		HI there,

> 
> 
> 
> 	Hey,
> 
> 	I recently installed FreeBSD 2.0.5 to replace my overloaded
> 	Linux box.  We run an ftp site that almost as popular as
> 	Walnut Creek's (roughly 400,000 file transfers per month).

	Do _not go with 2.0.5 - it is very unstable ...
	I run 2.10 Stable on 7 _big servers ( 4000 -10000
	accounts each) - no problemo.
	I have maxusers=128 usually and just ignore :) the
	message about maxusers being over 64. Didn't have much time
	to dive into the sources to see why does it complain
	at all.

> 
> 	Naturally I found that the generic kernel would run out of 
> 	file handles almost immediately (5 min. max.) that was 
> 	at 24 incoming sessions.  Besides I certainly planned on
> 	rebuilding the kernel anyway.  So I config'd to 128 --
> 	it complained that this was > 64, so I brought it down
> 	to 64 and rebuilt.
> 
> 	Stop reading if you've heard this one before.....
> 
> 	Ahh -- this must be news then -- she reboots!  The 2.0 kernel
> 	(which I had tried first) would wait ten minutes (getting upto
> 	70 ftp sessions or so) and then panic.  2.0.5 had the grace to
> 	refrain from lulling me into a false sense of security by
> 	dying immediately.

	Hmmmm. it should complain loudly about being unable
	to open new file(s) because of lack of resources -
	but it definitely shouldn't panic because of it


> 
> 	It was a simple matter to reboot on the generic kernel,
> 	'ifconfig de0 down' and build one with MAXUSERS set to 
> 	32.  That was stable but would run out of file handles
> 	at ~95+ users (under a half hour).  So I built her again
> 	with a setting of 63 and brought her back up.  I've been
> 	monitoring her for a week now with a cron job to mail me
> 	ftpcount's every hour and an entry in rc.local to mail me
> 	a dmesg on every reboot (root is .forwarded to another box
> 	inside -- from which I'm mailing this).
> 
> 	There have been no more reboots. The ftpcount has been
> 	averaging 150 and the I wrote a test to start 200 concurrent
> 	processes (while 50 users were in from outside) at which
> 	she didn't even blink.
> 
> 	So, moral of that story is -- don't set MAXUSERS to 64.
> 	This is a Pentium 90 with 64Mb of RAM, NCR PCI SCSI and
> 	a DEC PCI ethernet (only about a Gig online).  Obviously
	
	weird :))

	Rashid