Re: [SLUG] self reboot solving ?

[Martin Visser]

As James indicated, start looking at /var/log/messages and /var/log/syslog,
which might show bad things occurring before the apocalyptic kernel panic
(if that is what is happening).

Netxt, though I haven't done this sort of thing for a while,  you can
arrange for processes and/or the kernel to "dump core" into the file system
which can be analysed with various utilities.

>From what I have read, if you set up the kernel crashdump facility, in the
event of a kernel panic another crashdump kernel can start and write a
snapshot of the runtime kernel to disk.

Have a look at this for a starting point.

https://wiki.ubuntu.com/Kernel/CrashdumpRecipe

However as James has pointed out it could be a host issue, in the way it
presents the virtual hardware to your guest. If the host does do something
bad you just may not see it (and the guest-based crashdump I have mentioned
above won't help). Your provider could be able to provide some logs that
would indicate at least the host sees concerning the untimely reincarnation
of your guest ;-)

Regards, Martin

martinvisse...@gmail.com
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Re: [SLUG] self reboot solving ?

[James Gray]

On 27/05/2011, at 11:19 AM, Voytek Eymont wrote:

> 
> On Fri, May 27, 2011 12:13 pm, James Gray wrote:
> 
>> On 27/05/2011, at 11:08 AM, Voytek Eymont wrote:
> 
>> I had a similar problem with a virtual linux server a while back.  Turned
>> out that presenting it with multiple VCPUs was the culprit.  Reducing it
>> back to a single VCPU fixed it.  As for how I figured that out - I went
>> back through the change logs and found that another engineer decided it
>> needed more CPU grunt and gave it another VCPU...not long after that we
>> started getting random reboots about once every 24-36 hours.  Although we
>> went through a lot of "what about this, what about that" before we
>> thought of checking the VM configuration and hypervisor changes.
>> 
>> My advice would be go back over what has changed on you virtual machine
>> AND your hypervisor.  Sometimes the most inane changes can lead to odd
>> behaviour.
> 
> James, thanks
> 
> I'm very new to this virtual host stuff
> 
> all I have access is the virtual host, this what you're suggesting needs
> admin of the actual hardware, yes?

Yep.  The "hypervisor" is the controlling "shell" that provides management and 
translation between the physical hardware and the virtual guest.  The 
hypervisor is usually something like VMware's vSphere or ESXi, XEN, or even 
VirtualBox or Parallels.  The latter pair are apps that run on top of an 
existing OS whereas the the others are operating systems in their own right.

If your hosting provider has made changes to the hypervisor and you don't have 
control of that (which is usually the case) the best bet would be to contact 
them and ask if they have made any changes coinciding with when you started 
experiencing problems.  Also, you might want to turn up the logging on your 
Linux server as you might get some clues about what is causing the reboot by 
messages leading up to it.  You might start seeing weird disk/IO/memory/CPU 
messages then BAM! Server reboots.  Obviously, whatever is ACTUALLY causing the 
reboot wont be logged (the kernel is drooling in the corner by that stage) but 
clues are gold when you don't have root cause.

Good luck :)

Cheers,

James

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Re: [SLUG] self reboot solving ?

[Voytek Eymont]

On Fri, May 27, 2011 12:13 pm, James Gray wrote:

> On 27/05/2011, at 11:08 AM, Voytek Eymont wrote:

> I had a similar problem with a virtual linux server a while back.  Turned
> out that presenting it with multiple VCPUs was the culprit.  Reducing it
> back to a single VCPU fixed it.  As for how I figured that out - I went
> back through the change logs and found that another engineer decided it
> needed more CPU grunt and gave it another VCPU...not long after that we
> started getting random reboots about once every 24-36 hours.  Although we
> went through a lot of "what about this, what about that" before we
> thought of checking the VM configuration and hypervisor changes.
>
> My advice would be go back over what has changed on you virtual machine
> AND your hypervisor.  Sometimes the most inane changes can lead to odd
> behaviour.

James, thanks

I'm very new to this virtual host stuff

all I have access is the virtual host, this what you're suggesting needs
admin of the actual hardware, yes?



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Re: [SLUG] self reboot solving ?

[James Gray]

On 27/05/2011, at 11:08 AM, Voytek Eymont wrote:

> I have a virtual Ubuntu machine running MAP+Postfix in service few weeks;
> 
> as of few days ago the system started self-rebooting once a day or so
> 
> how to diagnose the reason ?
> 
> ~# uname -a
> Linux 2.6.32-30-generic-pae #59-Ubuntu SMP Tue Mar 1 23:01:33 UTC 2011
> i686 GNU/Linux
> 
> top - 11:07:30 up 10:38,  2 users,  load average: 0.02, 0.22, 0.29
> Tasks: 154 total,   1 running, 153 sleeping,   0 stopped,   0 zombie
> Cpu(s):  0.7%us,  0.7%sy,  0.0%ni, 98.3%id,  0.3%wa,  0.0%hi,  0.0%si, 
> 0.0%st
> Mem:508864k total,   445384k used,63480k free,33108k buffers
> Swap:   364536k total,   121620k used,   242916k free,   144904k cached

I had a similar problem with a virtual linux server a while back.  Turned out 
that presenting it with multiple VCPUs was the culprit.  Reducing it back to a 
single VCPU fixed it.  As for how I figured that out - I went back through the 
change logs and found that another engineer decided it needed more CPU grunt 
and gave it another VCPU...not long after that we started getting random 
reboots about once every 24-36 hours.  Although we went through a lot of "what 
about this, what about that" before we thought of checking the VM configuration 
and hypervisor changes.

My advice would be go back over what has changed on you virtual machine AND 
your hypervisor.  Sometimes the most inane changes can lead to odd behaviour.

Cheers,

James

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[SLUG] self reboot solving ?

[Voytek Eymont]

I have a virtual Ubuntu machine running MAP+Postfix in service few weeks;

as of few days ago the system started self-rebooting once a day or so

how to diagnose the reason ?

~# uname -a
Linux 2.6.32-30-generic-pae #59-Ubuntu SMP Tue Mar 1 23:01:33 UTC 2011
i686 GNU/Linux

top - 11:07:30 up 10:38,  2 users,  load average: 0.02, 0.22, 0.29
Tasks: 154 total,   1 running, 153 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.7%us,  0.7%sy,  0.0%ni, 98.3%id,  0.3%wa,  0.0%hi,  0.0%si, 
0.0%st
Mem:508864k total,   445384k used,63480k free,33108k buffers
Swap:   364536k total,   121620k used,   242916k free,   144904k cached



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Re: [SLUG] Linux in Australia in 2012 - trends..

[Matthew Hannigan]

On Wed, May 25, 2011 at 08:50:47AM +1000, David Lyon wrote:
> [ .. ] 
> Yes Ubuntu is nice, but Android is surely set to be a competitor ?

ChromeOS is the more direct competitor.  The big selling point is 
no admin necessary and safer browsing (probably) and more virus resistant. 
(possibly)

Of course, TANSTAAFL.  You pay in reduced privacy.


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Re: [SLUG] Experimental Live video streaming from SLUG tomorrow!

[Jon and Hannah]

Tim,

This is an awesome idea! I've wanted to go to a Slug meeting for ages now, but 
have never had the time! I should be able to get to computer though!

cheers

Jon

On Thu, 26 May 2011 10:01:56 am Tim Ansell wrote:
> Hello everyone,
> 
> I'm currently trying to set up live video streaming for events held at
> Google like FP-Syd, SLUG and SyPy. Tomorrow at SLUG we are going to try a
> second round of testing. There is no guarantee that it will work at all, so
> please don't rely on the stream but if your bored and want to help out,
> please do join in!
> 
> If you would like to participate in the trial, please go to the following
> URL from 6pm onwards;
>   http://tims-video.appspot.com/slug
> 
> As a backup the following JustinTV channel should also be transmitting the
> same stream, please use the primary video channel to help with testing.
>   http://www.justin.tv/mithro1
> 
> The system has twitter and IRC integration, so tweet with the
> #sydlughashtag, and join
> the
> irc://irc.freenode.org/#slug IRC channel.
> 
> Tim 'mithro' Ansell
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