The case against LVM

[Robin Laing]

Karl Larsen wrote:
> Ewan Mac Mahon wrote:
>> On Wed, Aug 01, 2007 at 12:10:41PM +0930, Tim wrote:
>>> On Wed, 2007-08-01 at 02:22 +0100, Ewan Mac Mahon wrote:
>>>> I have a server with ~16Tb of storage that's shared amongst research
>>>> groups in a university dept. Each group has their own filesystem, and
>> <snip>
>>>> That machines predecessor didn't use LVM and it was a nightmare to
>>>> admin with free space fragmented all over the place. I wouldn't go
>>>> back.
> 
>     There are issues about how you partition a giant hard drive like 
> that. I forget just how many partitions your allowed but it is small 
> compared to the size. I guess your the IT expert and you have REAL 
> Experience to back your support for LVM.
> 
>>> I'm curious about two things:  Wouldn't resizing LVM involve fragmenting
>>> the drive, in another way? 
>> Only physically; if I allocate space to one filesystem, then create
>> another, then extend the first one then the physical storage for the
>> first one will be in two chunks with the second fs sitting between them.
>> The point of LVM is that I don't need to care about it since it appears
>> as a single logical space.
>>> And, doesn't things like file quotas let you
>>> stop some users from using all available space?
>>>
>> Up to a point, but group quotas are rather less straightforward, IMHO.
>>
>> There's the further point that I have some additional storage to add to
>> this system; once I've done that with LVM I can simply seamlessly extend
>> any of the existing filesystems onto that storage; while you could
>> probably divide up the pie with quotas, there'd be no way to make the
>> whole pie bigger.
>>
>> Ewan
>>
>>
>     At my school the departments all have a computer that backs up all 
> the computers in the departments. The Hard Drive(s) are smaller but do 
> the job.
> 
>     At home I have a tiny 160 GB and I do not need LVM and in fact it 
> makes for even more wasted space than using the old /.
> 

On my home machine I started with the same size drive (RAID 1).  A year 
later I was at it's limit.  At that time, the cost of high capacity 
drives were out of my range.  I added two drives as a second raid 1 
device and created an LVM.  Copied all data across and verified it then 
added the old drives to the system to increase the total space 
available.  Damn multimedia files take up so much space.  :)

I have had some issues with LVM in the past but the move to F7 was easy, 
including both the raid and LVM drives.  Even when I had drive issues 
(bad power supply), I didn't have that much of a problem fixing it.  Of 
course the RAID helped here.

For /home I will stick with RAID and LVM.  It makes it easy to increase 
the space as needed.  Especially with with using the home computer as a 
Multimedia Server.

The only issue that I see is recovery of data from a single drive 
outside the LVM.  But this could also be a benefit in security if the 
drive gets stolen.

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Robin Laing