Re: [vserver] LVM within Vserver guests

From: Ted Barnes <madogdevelopment_at_gmail.com>
Date: Wed 05 Feb 2014 - 22:07:42 GMT
Message-ID: <52F2B62E.5050605@gmail.com>

Thanks so much Marco (do you prefer to be called "Kiko"?)...appreciate
the help (the clones start in about 20 seconds or so, it would appear
much of the time being consumed by the time it takes to start the
"avahi-daemon"). On another post, someone said kpartx doesn't work if
you're using encrypted drives...so I may have to go a different route.
I'll take a look at the hashify approach, though it would appear that
even if it allows me to restore a guest quickly to it's original state,
it will take a "long time" to copy back in the /home data. If you know
of anyone who might help on a "consulting basis" who might help me solve
this, let me know? Thx, Ted (madogdevelopment@gmail.com)

On 02/05/14 15:39, Marco Carnut wrote:
> Hi Ted,
>
>
>> 1) I downloaded the VM
>> (http://www.postcogito.org/vsdemo0.5-ubuntu10_04-32bit.7z ) and it runs,
>> but am unsure what I should look for. Within the Ubuntu VM, a message
>> comes up (Welcome to Kiko's 'Vservers on the Desktop' Demo!", and there
>> are a number of links in the upper panel to Firefox, Corporate Firefox,
>> LibreOffice etc. The pw allows me to get root access, but as best I
>> can tell the vserver is not using an LV. Can you throw me a tip as to
>> what I might look for to see how you configured partitions etc.?
>>
> You're correct. In this demo, I didn't use LVMs at
> all -- I used unified (or "hashified") clones because
> they reuse disk space AND memory, allowing much more
> vservers in the same memory footprint. This is my "2nd
> gen" solution; the LVM thing was my "1st gen"
> approach.
>
> In the demo, the "Banking Firefox" icon is the one
> that best describes the fundamental idea I wanted
> to achieve: a vserver that re-clones itself out of
> a "master" template, providing a fast "self-cleaning
> reinstall" effect in case of breach. Actually, we
> can go further: if re-cloning is cheap and fast,
> we don't even try to detect that we've been breached;
> we simply re-clone every time.
>
>
>> 2) My Linux Vserver clones take about 10 min to complete...my
>> impression is yours get completed much more quickly. Is that possibly
>> because I'm not using hashify, have a slower machine, or have a larger
>> vserver to clone (with the Mate desktop etc.)?
>>
> Yep, that's primarily because you didn't hashify them.
> When you hashify, almost everything is done with
> hard links, which are much faster to create and
> take almost no disk space. When you don't hashify,
> the clone operation actually copies the whole contents
> of every file in the vserver, which takes much longer
> and duplicates the disk space usage.
>
> BTW, how long did it take in your system for the
> clones to start?
>
>
>> 3) I've been looking at "kpartx" as a way to create nested LVMs,
>> assuming I'd clone a new Vserver, create some nested LVMS, and then move
>> the Vserver's "/home" to one nested LVM and everything else to another
>> (my assumption being this may not work but am experimenting...). Do you
>> use "kpartx" in your work, or some other approach when creating nested
>> LVMs? When I issue something like "kpartx -av /dev/vg2/LVM" I get no
>> output on the command line and so am wondering if kpartx works with my
>> set up (Encrypted RAID, LVM, Wheezy).
>>
> As I said, I used LVMs in an earlier version of this
> system. At the time I used plain lvs, I didn't feel
> a need to have them nested. There was a clone script
> that snapshotted a particular lv, mounted it and
> started the vserver in it. The annoying thing was
> that I had to have nearly one lv and filesystem
> per vserver, which prevented me from using hashified
> vservers. The LVM snapshotting did save some disk
> space, but because of the different filesystems,
> we had many idential versions of libc, bash, etc., loaded several times,
> wasting a lot of memory.
> And, overall, the solution ended up being quite
> complicated. When I changed to hashified cloned
> vservers in a same filesystem, all these downsides
> went away and the overall solution ended up a lot
> simpler.
>
> The demo VM you got does a lot more than that;
> it compartimentalizes the X Window System, Pulse
> Audio, etc., because it was meant to be a "desktop
> system". In a server system, it gets much simpler.
> Take a look at the "vstart/vclone" scripts.
>
> Hope this helps.
>
> -Marco.
>
>
>
Received on Wed Feb 5 22:07:51 2014

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