Re: [vserver] Guest on GlusterFS - /var/run/utmp: File too large

From: Oliver Welter <mail_at_oliwel.de>
Date: Wed 03 Oct 2012 - 10:37:56 BST
Message-ID: <506C0774.5050402@oliwel.de>

Hi Gordan,

On 03.10.2012 11:13, Gordan Bobic wrote:
> On 10/03/2012 09:54 AM, Oliver Welter wrote:
>> Hi Herbert
>>
>> On 01.10.2012 17:39, Herbert Poetzl wrote:
>>> On Mon, Oct 01, 2012 at 01:43:19PM +0200, Oliver Welter wrote:
>>>> Hi,
>>>> I am experimenting with vserver and glusterfs - I guess that this is a
>>>> glusterfs issue but perhaps somebody here has an idea.
>>>> I am creating my root filesystem from a read-only root and an overlay
>>>> filesystem using aufs. This is working fine with normal
>>>> blockdevices. I
>>>> now tried to replace the writeable partition using a glusterfs mount
>>>> point, which results in
>>>> fakerunlevel: open("/var/run/utmp"): File too large
>>> sounds like the file is too large :)
>>>
>>> check the file sizes on all involved filesystems and
>>> compare them to the maximum allowed file size
>> Well - the utmp file remaining on the disk after abort is 384 bytes and
>> I have no problems to create some larger files so I guess there is some
>> issue with locking or the like. As said, I assume thats not really
>> related to vserver itself...
>
> It sounds like you have bumped into one of the many issues with
> GlusterFS that arise when you try to use it as a rootfs. You may want
> to have a read through the glusterfs-devel mailing list archives for
> issues like this that I came across when I was using it for similar
> things (e.g. Open Shared Root). The particularly common claim among
> the developers at the time was that "they couldn't reproduce it" - in
> reality they just couldn't be bothered to put together a few VMs to
> test the kind of a setup required to run GLFS as rootfs. From what
> I've seen about GLFS, not much has changed since a few years back
> other than version number inflation and a RH badge.
>
> Do bear in mind that GLFS is extremely susceptible to split-braining
> if you are hoping to do anything interesting like sharing rootfs-es.
> This is borne out of it's lack of having any notion of quorum and node
> fencing.
>
Hm, not nice - but: I did some more tests an having a single glusterfs
as the root partition seems to work (well, the server starts and runs
for 5 mins), I get the above errors only if I use glusterfs as part of
aufs, which results in that kind ofg "sandwich-fs":

sda1 sda2
glusterfs
   (rw) aufs (ro)
    vserver root"partition"

I dont plan any concurrent use, I am currently running the same setup
using drbd to mirror the rw-portion to a second box for failover, so the
only thing that matters is that writes are commited "immediately" to the
second node, which is the case according to the docs.

Oliver

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Received on Wed Oct 3 10:38:03 2012
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