From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx08.extmail.prod.ext.phx2.redhat.com [10.5.110.12]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id n9JIfq4V020011 for ; Mon, 19 Oct 2009 14:41:52 -0400 Received: from mail-gx0-f221.google.com (mail-gx0-f221.google.com [209.85.217.221]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n9JIffpw022364 for ; Mon, 19 Oct 2009 14:41:41 -0400 Received: by gxk21 with SMTP id 21so5540795gxk.10 for ; Mon, 19 Oct 2009 11:41:41 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Drew Date: Mon, 19 Oct 2009 11:41:21 -0700 Message-ID: Subject: Re: [linux-lvm] Total free space using added VGs and LVs Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Lou Arnold Cc: LVM general discussion and development > But I thought that the purpose of LVM was to make a number of partitions > look like one big one. So I can understand that with an added volume group, > the filsesystems are separate, but for my (2) below, I expected all LVM-type > partitions to seen as one large one. The purpose of LVM is to make a bunch of physical drives look like one big pool of storage space. A Volume Group is a container into which you plug physical volumes (drives) so that the logical volumes can allocate space from the pool (volume group) as needed. > 1) Why would you want several logical volumes in one volume group? The same reason(s) you would want to partition a regular hard drive. Maybe you only want /home to have 20GB so your kids can't flood the computer with downloaded music. Maybe you want /var/www to have restricted permissions so your home web server is less vulnerable to hackers. Maybe you're running a PVR application like MythTV and want a high-performance filesystem like XFS for storing recorded shows. All of these can be done with logical volumes, and are often easier under LVM. > 2) Why would you want several volume groups at all? You don't need multiple volume groups on a single machine. There are certain uses though in which it is beneficial, usually in commercial use. -- Drew "Nothing in life is to be feared. It is only to be understood." --Marie Curie