From owner-freebsd-questions@freebsd.org Tue Jan 17 15:26:21 2017 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CC05ACB3D0D for ; Tue, 17 Jan 2017 15:26:21 +0000 (UTC) (envelope-from freebsd@qeng-ho.org) Received: from bede.home.qeng-ho.org (bede.qeng-ho.org [217.155.128.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "fileserver.home.qeng-ho.org", Issuer "fileserver.home.qeng-ho.org" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 670B81FBB for ; Tue, 17 Jan 2017 15:26:20 +0000 (UTC) (envelope-from freebsd@qeng-ho.org) Received: from arthur.home.qeng-ho.org (arthur.home.qeng-ho.org [172.23.1.2]) by bede.home.qeng-ho.org (8.15.2/8.15.2) with ESMTP id v0HFQHKb049105 for ; Tue, 17 Jan 2017 15:26:17 GMT (envelope-from freebsd@qeng-ho.org) To: FreeBSD-Questions From: Arthur Chance Subject: Boot environments and /var - what should be shared/unshared? Message-ID: Date: Tue, 17 Jan 2017 15:26:17 +0000 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Jan 2017 15:26:21 -0000 I've been using beadm boot environments for a while now, but still haven't seen a definitive reference for which parts of /var should be shared across boot environments and which should be per environment. Is there such a document, or is everybody still busking it? Some top level directories in /var seem fairly obviously in need of sharing, others less so, and /var/db seems to be a horrible mix of stuff that could be shared across releases and stuff that might break horribly if shared over major revisions. (That's "might" because I have no idea if it would in practice.) I doubt whether any of this would matter (except for space) if one simply rolled forward monotonically, but a roll back because of problems, or simply switching between development environments, could lose necessary updates if the directory hadn't been shared when it should have been. -- By June 1949, people had begun to realize that it was not so easy to get a program right as had at one time appeared. It was on one of my journeys between the EDSAC room and the punching equipment that the realization came over me with full force that a good part of the remainder of my life was going to be spent in finding errors in my own programs. -- Maurice Wilkes