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From Chiradeep Vittal <Chiradeep.Vit...@citrix.com>
Subject Re: CentOS System Offering Thread
Date Thu, 13 Dec 2012 22:59:50 GMT
Yes, it is for performance reasons.
CentOS 
 -has a different place for network init scripts
 -has a different initialization scheme (chkconfig vs LSB init)
 -has a different place to initialize iptables

Centos also may use GRUB-legacy vs GRUB2 for booting.
The current systemvm uses GRUB-legacy since XS 5.6 only supported
GRUB-legacy, but it might be time to move on.

A more suitable systemvm build script might be based on veewee/vagrant,
along with qemu-img to do the final conversion to vhd/qcow2

--
Chiradeep

On 12/13/12 10:29 AM, "Anthony Xu" <Xuefei.Xu@citrix.com> wrote:

>32-bit PV might have better performance than 64-bit PV on XEN,
>In 64 bit mode, there are only ring 0 and ring 3, both Guest OS and guest
>application are running on ring3 , application system call needs to be
>trapped into hypervisor and then be injected into guest OS.
>In 32 bit mode, there are ring 0, 1, 2, 3.   Guest OS is running on ring
>1, application is running on ring 3, hypervisor doesn't need to trap
>system call.
>
>That might be one of reasons dom0 is 32 bit in XenServer/XCP.
>
>Anthony
>
>> -----Original Message-----
>> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
>> Sent: Thursday, December 13, 2012 10:20 AM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> The choice of 32-bit OS may be to support legacy servers, but I really
>> don't know.
>> 
>> 
>> -----Original Message-----
>> From: Musayev, Ilya [mailto:imusayev@webmd.net]
>> Sent: 13 December 2012 4:50 PM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> I did.. reviewed buildsystemvm.sh script - seems self-explanatory.
>> 
>> There are 2 major parts to this task as I see it.
>> 
>> Part1
>> System Image Side:
>> We  need to alter the "debootsrap" to "mock" and change debian specific
>> configs to redhat.  Once functional - I need to create 3 versions of
>> the template for VmWare, Xen and KVM. I have VmWare in house - no
>> Xen/KVM yet - we can deal with this - once I get there.
>> 
>> Part2
>> Systemvm.iso will need to be updated and include rhel version of the
>> patch scripts we run on power on.
>> 
>> 
>> What is the reason for running 32bit OS vs 64? Are we open to changing
>> that to 64bit - which would probably benefit very large implementations
>> using basic zones. Or should we keep it 32 bit for consistency reason?
>> 
>> -----Original Message-----
>> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
>> Sent: Thursday, December 13, 2012 7:47 AM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> WRT to CentOS.  Did you survey the changes required?
>> 
>> Would be great to have these on a wiki page for future reference and
>> history tracking.
>> 
>> 
>> DL
>> 
>> 
>> -----Original Message-----
>> From: Musayev, Ilya [mailto:imusayev@webmd.net]
>> Sent: 12 December 2012 9:33 PM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> Donal
>> 
>> See response in line..
>> 
>> >> 1.  Can you remind me of the download link for the Wheezy systemVM?
>> I've only seen Squeeze.
>> 
>> I confused the names - I think - its squeeze - wheezy is the latest
>> offering with 3.x kernel. I guess by now you noticed I'm not debian
>> user :)
>> 
>> >> 2.  In addition to a Debian system VM, I'd like to see one and only
>> one CentOS VM in addition to Debian.  I get the impression that CentOS
>> has a different and desirable licensing regime, but do correct me if
>> I'm wrong.
>> 
>> I'm under impression CentOS has very liberal licensing structure. I
>> don't believe we should have an issue here - but I'm by no means a
>> licensing expert.
>> 
>> I think it's reasonable to have 1 other offering only..
>> 
>> Thanks
>> ilya
>> 
>> 
>> -----Original Message-----
>> From: Donal Lafferty [mailto:donal.lafferty@citrix.com]
>> Sent: Wednesday, December 12, 2012 3:34 PM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> 1.  Can you remind me of the download link for the Wheezy systemVM?
>> I've only seen Squeeze.
>> 
>> 2.  In addition to a Debian system VM, I'd like to see one and only one
>> CentOS VM in addition to Debian.  I get the impression that CentOS has
>> a different and desirable licensing regime, but do correct me if I'm
>> wrong.
>> 
>> DL
>> 
>> -----Original Message-----
>> From: Musayev, Ilya [mailto:imusayev@webmd.net]
>> Sent: 12 December 2012 8:06 PM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: RE: CentOS System Offering Thread
>> 
>> Joe
>> 
>> Your point is clear and well taken. Nobody wants to be in business of
>> maintaining myriad of distros out there for something that should not
>> be changed anyway.
>> 
>> I see two solutions then:
>> 
>> 1) update the existing debian wheezy image to reflect latest fixes -
>> which is probably something that should do anyway.
>> 
>> 2) maybe have a section of  - "user submitted and unsupported" system
>> offerings? We can clearly state - we support 1 type of offering and
>> other offerings are optional and unsupported  - but your own
>> responsibility and should be used by advanced users only.
>> 
>> Thoughts?
>> 
>> Regards
>> -ilya
>> 
>> -----Original Message-----
>> From: Joe Brockmeier [mailto:jzb@zonker.net]
>> Sent: Wednesday, December 12, 2012 11:02 AM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: Re: CentOS System Offering Thread
>> 
>> On Tue, Dec 11, 2012, at 11:32 PM, Marcus Sorensen wrote:
>> > This is pretty important.  Anyone should be able to roll their own,
>> > rather than relying on a single potentially out-of-date image. It
>> > seems like it would be pretty simple and straightforward on the face
>> > of it, however many of the scripts have been written specifically for
>> > Debian. I'd honestly be ok with having to stick to a particular
>> distro
>> > if I at least had clear instructions on how to make my own, I
>> > understand the need to program against a single defined userspace.
>> 
>> I see a potential problem with this.
>> 
>> Any scenario where users are customizing part of the stack means
>> additional variables which means additional problems. If we target
>> Debian, trying to create a system VM from CentOS/RHEL means different
>> libraries, etc. - which means a number of potential problems cropping
>> up where there were none before.
>> 
>> I'm not saying users *shouldn't* be able to do this - just that I
>> haven't noticed anyone raising the issue that we'll probably start
>> seeing a fair number more bugs if replacing the system VM becomes a
>> standard practice. There's a reason, for instance, that Linux vendors
>> don't support custom kernels - and what's being proposed here is
>> swapping out an entire OS.
>> 
>> It's going to make things a bit more tricky when someone reports a bug
>> and they're using a roll-your-own system VM and the people doing the
>> testing are using a different one.
>> 
>> Again - not saying we shouldn't do this, but I'd like to see that given
>> a bit more consideration when we're discussing the issue.
>> 
>> Best,
>> 
>> jzb
>> --
>> Joe Brockmeier
>> jzb@zonker.net
>> Twitter: @jzb
>> http://www.dissociatedpress.net/
>> 
>> 
>> 
>> 
>> 
>


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