From owner-freebsd-jail@FreeBSD.ORG Mon Feb 6 20:29:20 2012 Return-Path: Delivered-To: freebsd-jail@FreeBSD.org Received: from mx2.freebsd.org (mx2.freebsd.org [IPv6:2001:4f8:fff6::35]) by hub.freebsd.org (Postfix) with ESMTP id 535F0106566B for ; Mon, 6 Feb 2012 20:29:20 +0000 (UTC) (envelope-from dougb@FreeBSD.org) Received: from 172-17-150-251.globalsuite.net (hub.freebsd.org [IPv6:2001:4f8:fff6::36]) by mx2.freebsd.org (Postfix) with ESMTP id 5130314E518; Mon, 6 Feb 2012 20:29:19 +0000 (UTC) Message-ID: <4F30381E.2020100@FreeBSD.org> Date: Mon, 06 Feb 2012 12:29:18 -0800 From: Doug Barton Organization: http://SupersetSolutions.com/ User-Agent: Mozilla/5.0 (X11; FreeBSD i386; rv:10.0) Gecko/20120201 Thunderbird/10.0 MIME-Version: 1.0 To: freebsd-jail@FreeBSD.org X-Enigmail-Version: 1.3.5 OpenPGP: id=1A1ABC84 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Subject: Practical limit to number of jails on a given host? X-BeenThere: freebsd-jail@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Discussion about FreeBSD jail\(8\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 Feb 2012 20:29:20 -0000 Howdy, Thinking about implementing a poor-man's virtualization solution with lots'o'jails, and wondering what people think about the practical limits of such a system. I realize that part of the answer is going to depend on CPU and RAM, so let's assume for the sake of argument that the answer to that bit is, "Lots of both." So first question is, is there some sort of hard-coded limit somewhere? If not, what is the largest number of jails that you've created successfully/reliably on a system, and what are the specs for that system? On a related note, what are the limits in terms of mount points on the system and/or jails? I'm thinking of a fairly typical "nullfs mount the system, devfs, and 2 or 3 NFS mount points" per jail type of situation. And finally, has anyone run into trouble with a large number of IP addresses for the jails? ISTR that way back when, the IP addresses associated with a particular interface were stored in a linked list, so as you added more you would start seeing O(N) slowdown on a lot of network stuff in the kernel. Any thoughts or advice along these lines will be greatly appreciated. :) Doug -- It's always a long day; 86400 doesn't fit into a short. Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/