Re: [Vserver] Re: Basic Question

From: Fareha Shafique <fareha_at_eecg.toronto.edu>
Date: Tue 09 May 2006 - 15:04:08 BST
Message-ID: <4460A158.7080708@eecg.toronto.edu>

Corey Wright wrote:

>On Mon, 08 May 2006 13:30:45 -0400
>Fareha Shafique <fareha@eecg.toronto.edu> wrote:
>
>
>
>>The following is taken from the Short
>>Introduction, can someone please explain it to me:
>>"Resource sharing: Since vservers can share binaries and libraries
>>without interfering, a second vserver generally cost 40-100 megs of disk
>>space only. Most of this space is a copy of the packaging database.
>>Independent updates: Vservers are updated independently even if they
>>share binaries with other vservers."
>>
>>Does this mean, that as I install programs (like sshd, and other
>>packages) on my vserver that are already installed on my host server,
>>the binaries will be shared?
>>
>>
>
>search for "vhashify" on http://linux-vserver.org/alpha+util-vserver for
>the practical how-to. the resource sharing is not automatic; you must
>enable it.
>
>i'll try to explain the theory briefly.
>
>storage space is conserved because files only exist in one place, but are
>referenced within multiple vservers though special hard links.
>
>memory space is conserved because binaries and shared libraries (and any
>item in the file cache, i suppose) only exist in memory once, though many
>vservers may be executing/using the file. the idea is to extend the
>concept of "shared libraries" to vservers, so that just as a
>shared library may be referenced by multiple applications and it only
>exists in memory once, the same is true for a shared library referenced by
>multiple vservers (by way of vhashify).
>
>all the examples i have seen enable vhashify for vserver guests, not the
>host. i presume it is possible, but it is never applicable in my case
>because hard links are only shared on a single filesystem (where i mount my
>host's executables/libraries on /usr and my vservers on /home).
>
>hth.
>
>corey
>
>
Thanks, that explaination helps :)
Now, is it only libraries and binaries that can be shared or can a
vserver be an exact replica of the host. For example, how about if I
want the filesystem of vserver vs1 to be an exact replica of the host,
and only when I write/modify any file a local copy should be created for
vs1 (using COW)? Is this possible?

Thanks in advance.
-FS
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Received on Tue May 9 15:04:38 2006

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