[Lxc-users] Container Filesystem in a file (loopback mount)

[Daniel Lezcano]

On 09/30/2010 09:50 PM, Andy Billington wrote:
> On 30/09/2010 20:21, C Anthony Risinger wrote:
>    
>> On Thu, Sep 30, 2010 at 8:05 AM, Gordon Henderson<gordon at drogon.net>   wrote:
>>
>>      
>>> On Thu, 30 Sep 2010, Daniel Lezcano wrote:
>>>
>>>
>>>        
>>>> On 09/30/2010 11:04 AM, Gordon Henderson wrote:
>>>>
>>>>          
>>>>> Looking to put "hard" limits on a containers filesystem size by creating a
>>>>> fixed-length file, putting a filesystem in it, loopback mounting it, then
>>>>> using that as the containers root ...
>>>>>
>>>>> I've not tried it yet, but wondering if anyone has done anything like
>>>>> this? Any pitfalls? (Other than maybe performance)
>>>>>
>>>>>            
>>>> Yep, I tried, no problem.
>>>>
>>>>          
>>> Great.
>>>
>>>
>>>        
>>>> In a near future, we will be able to specify directly the image in
>>>> lxc.rootfs. The code doing that is ready but there are some problems with the
>>>> consoles I have to fix before.
>>>>
>>>>          
>>> Sounds good, thanks!
>>>
>>>        
>> in the past i used a btrfs filesystem, and put each system in a
>> subvolume; this let me create templates that were instantly cloneable,
>> and able to run within seconds.
>>
>> IIRC, you can't do this right now, but soon you will be able to place
>> quotas on the subvolumes.  also, you can snapshot them the make a
>> backup instantly.  just a suggestion, it worked extremely well.
>>
>> C Anthony
>>
>>
>>      
> I've been experimenting with btrfs and cloning this afternoon; once I'd
> got over an unrecoverable btrfs error and loss of all test data, it
> worked fairly smoothly. I wasn't using subvolumes or playing with quotas
> though, so not sure that helps this discussion :) With a few bits of
> easy scripting, creating new systems and starting them up was taking
> tens of  seconds; backups quicker - on a desktop PC, with the LXC host
> running inside a VMware virtual machine. The experience of losing an
> entire filesystem due to a btrfs fault though means I don't think it's a
> sensible route to take at this point .......
>    

Yeah, btrfs is still experimental. In the past, I did the same as 
Anthony without visible problems but when I tried recently I crashed my 
filesystem too. I am very impatient to see btrfs more mature because it 
looks very promising.