From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (mx1.redhat.com [172.16.48.31]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id jBK1gP132623 for ; Mon, 19 Dec 2005 20:42:25 -0500 Received: from spamtest2.viacore.net ([64.162.99.240]) by mx1.redhat.com (8.12.11/8.12.11) with ESMTP id jBK1gJjI007066 for ; Mon, 19 Dec 2005 20:42:19 -0500 Received: from spamtest1.spamtest.viacore.net (spamtest1.spamtest.viacore.net [192.168.201.101]) by spamtest2.viacore.net (Postfix) with SMTP id AE1A08143A for ; Mon, 19 Dec 2005 16:32:54 -0800 (PST) Received: from [10.15.1.15] (loather.viacore.net [10.15.1.15]) by spamtest1.spamtest.viacore.net (Postfix) with ESMTP id 6743F281146 for ; Mon, 19 Dec 2005 16:34:20 -0800 (PST) Message-ID: <43A75529.10809@tsss.org> Date: Mon, 19 Dec 2005 16:49:45 -0800 From: kelsey hudson MIME-Version: 1.0 Subject: Re: [linux-lvm] meaning of -L for snapshots ? References: In-Reply-To: Content-Transfer-Encoding: 7bit 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"; format="flowed" To: LVM general discussion and development Olivier Kaloudoff wrote: > Who can explain the usage of -L10M for my snapshot ? LVM snapshots have a limitation to how much data can change before the snapshot becomes invalid. So, by using -L10M, you're saying to keep the snapshot around until 10M of data has changed, then the snapshot becomes invalid. Because of the way LVM snapshots work, they require extra space on a volume. So, the size of your snapshot volume dictates how long it will remain valid. A good rule of thumb is between 10% and 20% of your primary volume's size. That way, 10 to 20% of the filesystem's contents can change and your snapshot will remain valid. Hope this clears some things up for you. -Kelsey