Changing partition sizes with LVM

[Eric S. Johansson]

Magnus Runesson wrote:
> On Tue, 2006-10-17 at 14:27 -0400, stan wrote:
>> I've got an Ubuntu machine that I have sliced up 2Tb worth of dsks (4 x
>> 500G). Now I find out I need to make one partion smaller, and move the
>> resulting free space to one of the other partions.
>>
>> This is a Daper machine. Is this do-able? Can any kind sould point me to a
>> HOWTO on this?
>>
> 
> Yes it is doable. Be aware that reducing disk and file systems is always
> a bit risky. So I recommend you to backup your data. I assume according
> to the subject that you have LVM based partitions.

You can reduce the risk by a couple of additional steps.
> 
> The four steps you should perform are:
> 1. Reduce the file system

reduce the filesystem to below your desired size.  For example if you 
want a 50 GB partition, shrink the filesystem down to 48 GB.  but under 
no circumstances should you shrink its smaller than your data set.  If 
you can't shrink to at least a GB smaller than your desired volume, you 
need a new disc.

> 2. Reduce the logical volume

reduce this to the size that you want.  For example, 50 GB

> 3. Expand the other logical volume.
> 4. Expand the file system.

no complaints with these two steps

Step 5: expand original file system to size of logical partition.  Most 
of the file system resizing tools will automatically resize from a 
smaller size up to the logical partition size.


> To be on the safe side: I recommend you to backup your data.

highly recommended.  It takes time but, it's worth it.