From mboxrd@z Thu Jan 1 00:00:00 1970 From: lembark@wrkhors.com Subject: Re: [linux-lvm] LVM newbie question. Message-ID: <6290000.1027433167@duke> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Tue Jul 23 09:09:02 2002 List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-lvm@sistina.com Have you read the FAQ? > When I do a pvcreate on say /dev/sda1 does that destroy all the existing > data on that partition? Why would you run pvcreate on a non-empty partition? The only thing you'd do after that would be creating LV's which will overwrite any data on the partition. > Which is better for pvcreate to be used on a whole disk (pvcreate > /dev/sda) and destroy all the underlying data or for me to merge all my > existing paritions over to PV to combine in a volume group? Is there any > advantage over either? Depends on how many disks you have. If have only a single disk then you're better off w/ a root partition and some swap outside LVM in case you have to recover from a situation in which LVM has problems. At that point you can parition a disk with, say, 120MB, 64MB, 2GB, w/ types 83, 82, 83, and 8e. This allows you to install the system w/ the 3rd partition as /usr if your distribution doesn't support LVM out of the box or use it for scratch space. If /usr is a mount point then the root can comfortably be 128MB. > I've read the LVM how-to and am stilll alittle confused having never done > it in practice. One part of the how-to said converting a root system to > LVM is not recommended. SHould your OS directories /var / /boot > etc all not be included in the LVM? That was the main idea behind me > implementing LVM so that specific partitions (say var) could be resized at > a later date if needed. If /usr is a mount point then having /boot as a separate mount is extraneous. If the machine isn't a 7x24 server you can probably get by with /var on LVM; for a hard-core system having /var on a partition is useful in case LVM fries. Make /var 320MB and use a separate /scratch partition for building new code, &c, and the only thing you'll need on /var is spooling and logs, which will be unlikely to outrun a 320MB partition. > Will I have any trouble restoring my system (which I backed up using dd > with a BS of 1024k) Do I have to make the LV the same size as my original > partition were for this to work? You cannot perform backups with dirty dump (dd). Use dump or cpio to back the system up before touching LVM. At the simplest: find / | egrep -v '/(proc|tmp|cache)/' | cpio -ov -Hcrc --io-size=$((80*1024*1024)) --file=$TAPE 2>&1 | tee /var/log/backup.log; would give a full system backup to the tape device. For a full backup using cpio -it --io-size=$((1024*1024*80)) --file=$TAPE to check the archive is highly recommended. Pick up a copy of Frisch, Essential System Administration, (3rd ed, O'Reilly Press, 2002) for recommendations on this; Nemeth, et al, Unix System Administrator's Handook (3rd ed) is also an excellent read. -- Steven Lembark 2930 W. Palmer Workhorse Computing Chicago, IL 60647 +1 800 762 1582