From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id j4A6r8O16791 for ; Tue, 10 May 2005 02:53:08 -0400 Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.196]) by mx3.redhat.com (8.12.11/8.12.11) with ESMTP id j4A6r2FY030099 for ; Tue, 10 May 2005 02:53:02 -0400 Received: by wproxy.gmail.com with SMTP id 68so1498083wri for ; Mon, 09 May 2005 23:53:02 -0700 (PDT) Message-ID: Date: Tue, 10 May 2005 12:23:02 +0530 From: Aditya Kulkarni Mime-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: [linux-lvm] LVM minor number allocation policy Reply-To: Aditya Kulkarni , 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" To: linux-lvm@redhat.com Hi all, Here are a few questions that I had related to minor numbers of logical volumes (LVs). First the questions, and then I will explain the reason why I ask these questions - [1] Suppose I create two LVs named vol1 and vol2. They have the following (major, minor) no.s. vol1 = (major=X, minor=0) and vol2 = (major=X, minor=1). Now I reboot the system. Is it guaranteed that vol1 and vol2 will retain their minor no.s? [2] Are there some options while creating LVs that we can use so that LVs are created with a particular minor number? [3] Suppose it is not guaranteed that LVs retain their minor numbers across system reboots. When the system is coming up, what policy it uses to assign minor numbers to LVs. For example, it could be based on any one of the following - 1. sort order of names of LVs. 2. Timestamp of creation of LVs. 3. Random Why I ask these: The issue of minor number remaining same is relevant to services being "highly available". In my case, it happens to be the NFS exported file system. The NFS file handle includes, among other things, the minor no. of the device on which the exported file system resides. In case the minor no. of LV is different on the failed-over-to system, we get the problem of stale file handles. Hence, I wanted to know how minor numbers are treated by LVM. -- Best Wishes, Aditya Kulkarni