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Switching from VMWare to OpenVZ? [message #42395] Tue, 12 April 2011 22:37 Go to next message
lists is currently offline  lists
Messages: 2
Registered: April 2011
Junior Member
From: *parallels.com
Hello everybody,

my workgroup and me do mostly simulations of complex organic compounds
and java programming. Since most of our programms run pretty unstable
we have been using VMWare to virtualize our Servers (Intel i7-920
Quad-Core/24GB DDR3 RAM/4TB RAID5).

A few months ago a colleague of mine tried OpenVZ and had a lot of
troubles setting it up.
I think the most confusing part for him was the RAM/Swap-Management.
So I thought before we try it again, we might just ask others if they
have a similar setup.

Currently we have 4 VM with 5 GB RAM/15GB Swap each. Since there is a
lot calculation involved it is always hard to say how much memory will
actually be used.

With OpenVZ we got the error "out of swap/memory" a lot.

What kind of settings, limits would you recommend with OpenVZ for that
particular setup?

Thanks for your help,
Chris
Re: Switching from VMWare to OpenVZ? [message #42396 is a reply to message #42395] Tue, 12 April 2011 22:45 Go to previous messageGo to next message
kir is currently offline  kir
Messages: 1645
Registered: August 2005
Location: Moscow, Russia
Senior Member

From: *parallels.com
13.04.2011 2:42 пользователь <lists@yhmail.de> написал:
>
> Hello everybody,
>
> my workgroup and me do mostly simulations of complex organic compounds and
java programming. Since most of our programms run pretty unstable we have
been using VMWare to virtualize our Servers (Intel i7-920 Quad-Core/24GB
DDR3 RAM/4TB RAID5).
>
> A few months ago a colleague of mine tried OpenVZ and had a lot of
troubles setting it up.
> I think the most confusing part for him was the RAM/Swap-Management.
> So I thought before we try it again, we might just ask others if they have
a similar setup.
>
> Currently we have 4 VM with 5 GB RAM/15GB Swap each. Since there is a lot
calculation involved it is always hard to say how much memory will actually
be used.
>
> With OpenVZ we got the error "out of swap/memory" a lot.
>
> What kind of settings, limits would you recommend with OpenVZ for that
particular setup?

What OpenVZ kernel are you using? Also, see
http://wiki.openvz.org/Resource_shortage


Kir Kolyshkin
http://static.openvz.org/userbars/openvz-developer.png
Re: Switching from VMWare to OpenVZ? [message #42397 is a reply to message #42396] Wed, 13 April 2011 00:05 Go to previous messageGo to next message
lists is currently offline  lists
Messages: 2
Registered: April 2011
Junior Member
From: *parallels.com
Hello,


we used 2.6.26-2-openvz-amd64 and Debian as the host.

What I don't understand is: Should we assigne all 24GB RAM plus swap
to each virtual machine?
Since there is no swap to use inside the container, this seems to be
the only way to avoid out of memory failures if you don't know what
your programm is going to consume...
or am I missing something?

Cheers,
Chris



Zitat von Kir Kolyshkin <kir@openvz.org>:

> 13.04.2011 2:42 ???????????? <lists@yhmail.de> ???????:
>>
>> Hello everybody,
>>
>> my workgroup and me do mostly simulations of complex organic compounds and
> java programming. Since most of our programms run pretty unstable we have
> been using VMWare to virtualize our Servers (Intel i7-920 Quad-Core/24GB
> DDR3 RAM/4TB RAID5).
>>
>> A few months ago a colleague of mine tried OpenVZ and had a lot of
> troubles setting it up.
>> I think the most confusing part for him was the RAM/Swap-Management.
>> So I thought before we try it again, we might just ask others if they have
> a similar setup.
>>
>> Currently we have 4 VM with 5 GB RAM/15GB Swap each. Since there is a lot
> calculation involved it is always hard to say how much memory will actually
> be used.
>>
>> With OpenVZ we got the error "out of swap/memory" a lot.
>>
>> What kind of settings, limits would you recommend with OpenVZ for that
> particular setup?
>
> What OpenVZ kernel are you using? Also, see
> http://wiki.openvz.org/Resource_shortage
>
Re: Switching from VMWare to OpenVZ? [message #42401 is a reply to message #42395] Wed, 13 April 2011 08:00 Go to previous messageGo to next message
Tim Small is currently offline  Tim Small
Messages: 24
Registered: April 2011
Junior Member
From: *parallels.com
On 12/04/11 23:37, lists@yhmail.de wrote:
> Hello everybody,
>
> my workgroup and me do mostly simulations of complex organic compounds
> and java programming. Since most of our programms run pretty unstable
> we have been using VMWare to virtualize our Servers (Intel i7-920
> Quad-Core/24GB DDR3 RAM/4TB RAID5).
>
> A few months ago a colleague of mine tried OpenVZ and had a lot of
> troubles setting it up.
> I think the most confusing part for him was the RAM/Swap-Management.
> So I thought before we try it again, we might just ask others if they
> have a similar setup.
>
> Currently we have 4 VM with 5 GB RAM/15GB Swap each. Since there is a
> lot calculation involved it is always hard to say how much memory will
> actually be used.
>
> With OpenVZ we got the error "out of swap/memory" a lot.
>
> What kind of settings, limits would you recommend with OpenVZ for that
> particular setup?

Dunno, it depends on how worried you are about one job potentially
taking out the whole server, and what the likelihood is of multiple VMs
all using a lot of RAM at the same time. If you are using Debian then
maybe use

vzsplit -n 1

or

vzsplit -n 2

or interpolate somewhere in between? The "vzcalc" tool is also worth
looking at, and I'd advise using Munin on the machine to track resource
usage (there are a couple of OpenVZ plugins).

It's also worth noting that 2.6.26 isn't a kernel version that OpenVZ
support, where as 2.6.32 (as used by Debian 6.0) is an OpenVZ supported
version, so you may want to switch to that before doing a new deployment.

In particular if you are using software RAID5, I've seen some IO
deadlocks on 2.6.26 with OpenVZ and software RAID - those problems
aren't present on 2.6.32.

Also worth noting is that I don't believe OpenVZ is planned to be
officially supported in the next Debian version (possibly it will be if
Linux Containers - LXC - aren't workable).

Cheers,

Tim.
Re: Switching from VMWare to OpenVZ? [message #42411 is a reply to message #42401] Wed, 13 April 2011 16:31 Go to previous messageGo to next message
dowdle is currently offline  dowdle
Messages: 261
Registered: December 2005
Location: Bozeman, Montana
Senior Member
From: *coe.montana.edu
Greetings,

----- Original Message -----
> It's also worth noting that 2.6.26 isn't a kernel version that OpenVZ
> support, where as 2.6.32 (as used by Debian 6.0) is an OpenVZ supported
> version, so you may want to switch to that before doing a new deployment.

Just to clarify, currently the only OpenVZ kernel branches marked as stable are:
RHEL4-2.6.8
RHEL5-2.6.18

The current OpenVZ devel kernels branches are:
RHEL6-2.6.32
2.6.32
2.6.27

2.6.27 is a long-term supported kernel by mainline I believe.

All of that is documented on the OpenVZ wiki here:
http://wiki.openvz.org/Download/kernel

> Also worth noting is that I don't believe OpenVZ is planned to be
> officially supported in the next Debian version (possibly it will be if
> Linux Containers - LXC - aren't workable).

It is my understanding that Parallels has actually hired a kernel developer in the states to work on LXC in the mainline. I haven't seen too much info on that yet... but yeah, the long-term future of containers in Linux is LXC. I don't really recommend LXC now unless you don't mind the bleeding-edge with bumps in the road.

TYL,
--
Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]


--
TYL, Scott Dowdle
Belgrade, Montana, USA
Re: Switching from VMWare to OpenVZ? [message #42415 is a reply to message #42411] Wed, 13 April 2011 18:46 Go to previous messageGo to next message
dowdle is currently offline  dowdle
Messages: 261
Registered: December 2005
Location: Bozeman, Montana
Senior Member
From: *coe.montana.edu
Greetings,

----- Original Message -----
> Just to clarify, currently the only OpenVZ kernel branches marked as
> stable are:
> RHEL4-2.6.8

Opps, make that RHEL4-2.6.9.

TYL,
--
Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]


--
TYL, Scott Dowdle
Belgrade, Montana, USA
Re: Switching from VMWare to OpenVZ? [message #42416 is a reply to message #42411] Wed, 13 April 2011 19:53 Go to previous messageGo to next message
Tim Small is currently offline  Tim Small
Messages: 24
Registered: April 2011
Junior Member
From: *parallels.com
On 13/04/11 17:31, Scott Dowdle wrote:
> Greetings,
>
> ----- Original Message -----
>
>> It's also worth noting that 2.6.26 isn't a kernel version that OpenVZ
>> support, where as 2.6.32 (as used by Debian 6.0) is an OpenVZ supported
>> version, so you may want to switch to that before doing a new deployment.
>>
> Just to clarify, currently the only OpenVZ kernel branches marked as stable are:
> RHEL4-2.6.8
> RHEL5-2.6.18
>
> The current OpenVZ devel kernels branches are:
> RHEL6-2.6.32
> 2.6.32
> 2.6.27
>
> 2.6.27 is a long-term supported kernel by mainline I believe.
>

OK, thanks for that - I thought 2.6.32 was OpenVZ supported already, but
clearly it isn't - the Debian version of 2.6.32 it is Debian-supported
already, of course (whereas 2.6.26 effectively isn't being supported by
Debian any more except for security updates).


2.6.32 is a long-term supported kernel by mainline (2.6.32.36 released
2011-03-27) - it's also the kernel which has been picked by RHEL6,
Debian 6, Ubuntu 10.04 LTS, and SLES.
I'd guess that 2.6.32 will be supported by Parallels in-time (just
because that's what RHEL6 uses), and is receiving active development,
bug fixes, etc.
2.6.27 probably won't be supported as a stable release by Parallels at
any point, I'd have thought (anyone know any different?).

> 2.6.27 is a long-term supported kernel by mainline I believe.

It is, and it appears to still be going (2.6.27.58 2011-02-09). I was
under the impression that it wasn't anymore, but I believe 2.6.32 is the
"main" long-term kernel at the moment.
2.6.26 isn't long-term (although in practise I believe the Debian Kernel
team did backport some stuff from it). 2.6.26 / Debian 5.0 will get
security fixes until next Jan, but no more bug fixes AFAIK.

On that basis, my advise based on personal experience would be to run
any new Debian OpenVZ deployments on Debian 6 / 2.6.32 ...

> I don't really recommend LXC now unless you don't mind the
> bleeding-edge with bumps in the road.

ACK. It doesn't do much in the way of resource usage limiting (at least
not on 2.6.32 last time I looked), so if you need that it'd be a
show-stopper.


Cheers,

Tim.

--
South East Open Source Solutions Limited
Registered in England and Wales with company number 06134732.
Registered Office: 2 Powell Gardens, Redhill, Surrey, RH1 1TQ
VAT number: 900 6633 53 http://seoss.co.uk/ +44-(0)1273-808309
Re: Switching from VMWare to OpenVZ? [message #42417 is a reply to message #42416] Thu, 14 April 2011 06:27 Go to previous message
ckkashyap is currently offline  ckkashyap
Messages: 9
Registered: March 2011
Location: India
Junior Member
From: *parallels.com
Hi Chris ... I am very keen to understand if you were able to get rid of the
"With OpenVZ we got the error "out of swap/memory" a lot." problem.

Regards,
Kashyap

On Thu, Apr 14, 2011 at 1:23 AM, Tim Small <tim@seoss.co.uk> wrote:

> On 13/04/11 17:31, Scott Dowdle wrote:
>
> Greetings,
>
> ----- Original Message -----
>
>
> It's also worth noting that 2.6.26 isn't a kernel version that OpenVZ
> support, where as 2.6.32 (as used by Debian 6.0) is an OpenVZ supported
> version, so you may want to switch to that before doing a new deployment.
>
>
> Just to clarify, currently the only OpenVZ kernel branches marked as stable are:
> RHEL4-2.6.8
> RHEL5-2.6.18
>
> The current OpenVZ devel kernels branches are:
> RHEL6-2.6.32
> 2.6.32
> 2.6.27
>
> 2.6.27 is a long-term supported kernel by mainline I believe.
>
>
>
> OK, thanks for that - I thought 2.6.32 was OpenVZ supported already, but
> clearly it isn't - the Debian version of 2.6.32 it is Debian-supported
> already, of course (whereas 2.6.26 effectively isn't being supported by
> Debian any more except for security updates).
>
>
> 2.6.32 is a long-term supported kernel by mainline (2.6.32.36 released
> 2011-03-27) - it's also the kernel which has been picked by RHEL6, Debian 6,
> Ubuntu 10.04 LTS, and SLES.
> I'd guess that 2.6.32 will be supported by Parallels in-time (just because
> that's what RHEL6 uses), and is receiving active development, bug fixes,
> etc.
> 2.6.27 probably won't be supported as a stable release by Parallels at any
> point, I'd have thought (anyone know any different?).
>
>
> > 2.6.27 is a long-term supported kernel by mainline I believe.
>
> It is, and it appears to still be going (2.6.27.58 2011-02-09). I was
> under the impression that it wasn't anymore, but I believe 2.6.32 is the
> "main" long-term kernel at the moment.
> 2.6.26 isn't long-term (although in practise I believe the Debian Kernel
> team did backport some stuff from it). 2.6.26 / Debian 5.0 will get
> security fixes until next Jan, but no more bug fixes AFAIK.
>
> On that basis, my advise based on personal experience would be to run any
> new Debian OpenVZ deployments on Debian 6 / 2.6.32 ...
>
>
> I don't really recommend LXC now unless you don't mind the bleeding-edge
> with bumps in the road.
>
>
> ACK. It doesn't do much in the way of resource usage limiting (at least
> not on 2.6.32 last time I looked), so if you need that it'd be a
> show-stopper.
>
>
> Cheers,
>
> Tim.
>
> --
> South East Open Source Solutions Limited
> Registered in England and Wales with company number 06134732.
> Registered Office: 2 Powell Gardens, Redhill, Surrey, RH1 1TQ
> VAT number: 900 6633 53 http://seoss.co.uk/ +44-(0)1273-808309
>
>
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