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-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o82FMX6N022525 for ; Thu, 2 Sep 2010 11:22:33 -0400 Received: from mail.bmsi.com (www.bmsi.com [24.248.44.156]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o82FMKoA031468 for ; Thu, 2 Sep 2010 11:22:21 -0400 Received: from sdg.bmsi.com ([192.168.9.34]) (authenticated bits=0) by mail.bmsi.com (8.14.3/8.14.3) with ESMTP id o82FMJRo000647 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 2 Sep 2010 11:22:20 -0400 Message-ID: <4C7FC12B.40009@bmsi.com> Date: Thu, 02 Sep 2010 11:22:19 -0400 From: Stuart D Gathman MIME-Version: 1.0 References: <2E9263050F8EE046972BE0510E7A71DA03D99F3C@SH-EXCHBE2.master.lsuhsc.edu> In-Reply-To: <2E9263050F8EE046972BE0510E7A71DA03D99F3C@SH-EXCHBE2.master.lsuhsc.edu> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] HDD failure - please help! 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 On 09/02/2010 07:50 AM, Patterson, James wrote: >> If you wanted RAID5, your best bet on linux is the md driver. >> Or else a hardware RAID controller. >> > I don't/didn't want RAID. > Based on your expectations, I think you *do* want at least RAID1. Raid 1 is simple to administer and understand. >> your first step is getting a copy of the metadata. >> There should be a copy at the beginning of each drive. >> > Yes. How do I access it? None of the drives will mount. I am thinking here that I should create a special boot disk with the LVM tools on it (they are not present on the FC11 boot iso, afaik). > You don't mount the PVs. Use the metadata extraction tool, I don't remember the name atm. If this was your boot filesystem, then you will need a LiveCD or new install. Since you will need a new disk anyway, I suggest you get the new disk that is *bigger* than the failing drive and install to it (but *not* overwriting the others) and leave a partition big enough to contain the PV from the failing drive. Remove the failing drive, and access it via USB - even if you have another drive slot. By taking steps to keep it as cold as possible during recovery, you can coax a few more sectors out of it. >> then you should look back a month or so in the archives >> > I looked...could you please be a bit more specific? I didn't see anything. > This should get you started: https://www.redhat.com/archives/linux-lvm/2010-July/msg00057.html > Well, truly, the only thing I've learned is never to use LVM if it's > going to cause me to lose data on all 5 drives when one goes down. The > logic behind it's use appears to be to just make life "easier" With jbod (which you likely have), the failure scenario is exactly the same whether you have 1 disk or 5. Part of your filesystem gets trashed, and you have to use low level tools to recover what remains if you don't have backups. What having 5 disks *does* do is make failure more likely. Suppose the probability of 1 disk *not* failing in a given year is .999 (3 sigmas). With jbod, the LV fails if *any* of the disks fail. The probability that none of them fail in a given year would then be .999^5 ~= .995. Your array is less reliable. By using RAID, you can make the array more reliable. RAID works by using multiple copies of data so that you don't lose anything on a single drive failure.