From owner-freebsd-questions@FreeBSD.ORG Tue Nov 1 20:46:41 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8A5CC16A420 for ; Tue, 1 Nov 2005 20:46:41 +0000 (GMT) (envelope-from user@dhp.com) Received: from shell.dhp.com (shell.dhp.com [199.245.105.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 16BF443D45 for ; Tue, 1 Nov 2005 20:46:40 +0000 (GMT) (envelope-from user@dhp.com) Received: by shell.dhp.com (Postfix, from userid 896) id 0B44131336; Tue, 1 Nov 2005 15:46:40 -0500 (EST) Date: Tue, 1 Nov 2005 15:46:39 -0500 (EST) From: user To: freebsd-questions@freebsd.org Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Subject: two quick conceptual questions RE: rsync (and rsyncing snapshots) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Nov 2005 20:46:41 -0000 Hello, I have started using rsync somewhat extensively and had two questions regarding its operation. First, how does rsync respond to, and perform, when the source filesystem is under very heavy change ? If I have a filesystem that I want to rsync up to a backup server, but that filesystem is _very busy_ with the creation, destruction and changing of files, how well does rsync perform, and how much does it interfere with the performance of the underlying filesystem that it is sending up to the backup server ? Related: it occurs to me that perhaps it would be better to snapshot the filesystem, mount the snapshot, and then rsync the snapshot. On the other hand, the filesystem is continuously altering the snapshot as files are destroyed or changed ... so perhaps this does not gain anything. Is rsyncing a snapshot of a busy filesystem always, ever or never easier than rsyncing the busy filesystem itself ? Finally, am I correct that there are _only two_ rsync comparison methods - the default checksum method, and the --size-only method ? Am I correct that rsync _always_ looks at the timestamp first, and then applies either checksum or size comparison ONLY IF the timestamps are different ? Thanks a lot.