Date: Mon, 18 Mar 2002 09:14:52 +0200 From: "Patrick O'Reilly" <bsd@perimeter.co.za> To: "Brendan McAlpine" <bmcalpine@macconnect.com>, <questions@FreeBSD.ORG> Subject: Re: HELP!! problem with new bsd mail server [solved kind of] Message-ID: <002701c1ce4c$99de3ec0$b50d030a@patrick> References: <B8BAF437.BA56%bmcalpine@macconnect.com>
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----- Original Message ----- From: "Brendan McAlpine" <bmcalpine@macconnect.com> > Hmmm > > The generic kernel is set for 32 maxusers, which should give me 532 > simultaneous processes. Qmail is only set for 100 concurrent connections at > its max......so would increasing the maxusers really help? Brendan, I'm not going to pretend to be authoritative on this subect, but here's what my gut tells me: The kernel maxuers setting is used as a scaling factor on various default settings in the kernel environment. One of these, as you noted, indicates that you should be able to have 532 concurrent processes (I'm assuming you did the math :). But there may be other limits you hit before then. For example, what about the numbers of simultaneous open file handles, or descriptors, or whatever the correct terminology is? My gut feel is that each qmail process is somewhat like a user (albeit a lightweight user), and requires a set of resources, somewhat like a user. If you have 'maxusers=32', and you have 100 simultaneous qmail processes running, my immediate reaction is that you are running more than I would have guessed your could system support 'out the box'. In an environment like yours where you have a reasonably heavy workload in a specific area I think you must accept that you will need to do some tuning of the system. > Is there a way to change this without re-compiling the kernel? No, not that I know of. 'sysctl kern.maxusers' will tell you what the current value is, but it is a read-only attribute, so you can't fiddle it via sysctl. Anyway, in my experience, rebuilding a kernel is not a particularly stressful exercise. It is certainly less stressful than living with a box that goes to sleep every day!!! > What about ICMP_BANDLIM? I've heard that sometimes that kernel option > causes networking problems. Has anyone heard about that? I have no idea whether this has any impact on your situation :( Again - I'm not sure that nudging maxusers will definitely solve your problem, but given the info you've told us I would say it is definitely worth a try. Regards, Patrick O'Reilly. --- Windows: "Where do you want to go today?" Linux: "Where do you want to go tomorrow?" FreeBSD: "Are you guys coming, or what?" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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