Re: LVM

[Stan Hoeppner <stan@hardwarefreak.com>]

Boyd Stephen Smith Jr. put forth on 6/15/2010 10:44 AM:
> On Tuesday 15 June 2010 04:52:10 Stan Hoeppner wrote:
>> Boyd Stephen Smith Jr. put forth on 6/14/2010 10:45 AM:
>>> On Monday 14 June 2010 03:11:56 Gerald C.Catling wrote:
>>>> Hi Guy's,
>>>> I am not a Debian user but I have seen references to LVM here.
>>>> I have 3 drives LVM'd to give me 1.3TB of storage space on my server.
>>>> The first drive of this set has died.
>>>
>>> Mostly, when one of your physical volumes is irrecoverably lost, so is
>>> any logical volume whose logical extents corresponded to one of the lost
>>> physical extents.
>>
>> This is why one should only use LVM on top of real hardware or software
>> RAID or a big SAN LUN.  
> 
> You should use LVM on top of whatever you have.  It's vastly superior to 
> partitioning as a way to divide a disk.  Even if you do not need to divide a 
> disk, the adds snapshotting and an on-line migration path above just using the 
> disk.

I meant this in the context of the OP's problem.  IIRC, he was using LVM to
span the capacity of 3 disks into a single large volume, increasing his
failure probability 3 fold.

Aggregate the space using RAID so you get some redundancy, then use LVM to
carve up the resulting space.  Don't use LVM to aggregate space, as it
increases the odds of total volume failure.

Using LVM to manage space on a single disk is fine.  Using it for spanning,
with no kind of redundancy, is not wise.

-- 
Stan