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On Sunday 22 March 2009, Albert Hopkins wrote: |
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> On Sat, 2009-03-21 at 14:13 -0700, BRM wrote: |
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> > With all the words of LVM2 going on, I feel it is only appropriate |
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> > to also mention the risk. |
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> > |
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> > On a desktop I had installed LVM2 considering that I did need to |
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> > upgrade partitions every now and then and my previous solution was |
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> > add another drive/partition and cross mount - e.g. like done with |
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> > /usr/local under /usr, which worked fairly well. LVM2 worked great |
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> > - until one of the drives crashed and I was trying to figure out |
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> > what was on it. From that pov, volume management is a pain. I did |
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> > figure out what I had mounted to it - but only after deconstructing |
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> > the LVM configuration file to match it up with what I had put |
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> > there. (And no, I had not yet gotten to doing an LVM soft-RAID |
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> > solution to map a single LVM partition to two drives, which would |
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> > certainly have helped.) I got my system working by adding a new |
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> > drive that was not part of the volume group, and removing the old |
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> > drives from the volume group. Fortunately, I had my volume setup so |
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> > that they one partition was not made up of non-overlaping |
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> > partitions on different drives. (e.g. partition A = sda1 + sda2 |
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> > instead of sda1 + sdb1.) |
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> > |
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> > So, unless you are looking to use LVM in a soft-RAID solution |
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> > between multiple physical drives, not multiple partitions on the |
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> > same drive, (e.g. partition A = sda1 + sda2, with mirror on |
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> > sdb1+sdb2), then I would not suggest it as should anything happen, |
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> > it'll make data recovery that much harder. |
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> > |
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> > Just 2 cents for the pot. |
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> |
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> With or without LVM if you lose a drive then you've lost the data on |
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> it. LVM does have the capability of assembling a partially damaged |
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> volume group just not a partially damaged logical volume which, when |
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> you think about it, makes sense. |
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> |
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> And you can also throw in the standard warning about backing up your |
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> data. |
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The point is that LVM adds an extra layer of complexity. |
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I used LVM paired with soft RAID, and when I needed to boot from a |
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liveCD I discovered that I had to rebuild the setup by hand. |
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When you're in trouble it is pristine to have a quick way out instead of |
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being "swamped". I had my notes and managed to reckon the configuration |
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(cold sweating!), but at the first occasion I reverted my system to |
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plain RAID. |
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Never used LVM for the few Gentoo server I manage. |
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That said backup+RAID is the way to go. |
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Cheers |
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Francesco |
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-- |
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Linux Version 2.6.28-gentoo-r3, Compiled #1 SMP PREEMPT Sun Mar 8 |
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12:38:59 CET 2009 |
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Two 1GHz AMD Athlon 64 Processors, 4GB RAM, 4018.04 Bogomips Total |
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aemaeth |
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