Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-20 Thread Sven Kieske


Am 18.06.2014 23:33, schrieb lee:
 No, I'm talking about an installer which can be used to create and to
 configure a VM image.  The resulting VM image would have all needed
 packages installed and be fully configured.

Yes, this is e.g. something you can do with saltstack salt-virt
or similar tools (especially the fully configured part).
but you could also use virt-builder/-installer + cloud-init
or various other tools.


 Does provisioning VM images not involve their creation?

No, not necessary.

-- 
Mit freundlichen Grüßen / Regards

Sven Kieske

Systemadministrator
Mittwald CM Service GmbH  Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-19 Thread George Dunlap
On Wed, Jun 18, 2014 at 2:48 PM, Sven Kieske s.kie...@mittwald.de wrote:
 I just dived a little in virt-builder and here are my findings:

 1. It's awesome!

 Am 18.06.2014 12:46, schrieb George Dunlap:
 So it looks like we might want to recommend three potential paths we
 could recommend people to explore:

 1) For basic CentOS VMs, use a CentOS-provided cloud image, with our
 custom metadata tweaking script.

 2. Why create a custom script if maybe virt-builder can handle it?
I don't know if you can point virt-builder to other images than
 those on libguestfs.org, but this should be possible, include an centos
 cloud-image on libguestfs.org and just use virt-builder

You can point virt-builder to another repo; and in fact, the guys on
the libguestfs development list said that them hosting their own
template repo was meant to be a temporary measure, and that long-term
they'd like to see distros hosting their own templates.

But as to why, did you miss that yum install libguestfs wants to
bring in an *additional* 178 packages, more than doubling the size of
a base installation? :-)

I think for a lot of people that will be fine; but I agree with KB,
that we should also have a really lightweight way for people to just
get VMs up and running.

 -George
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-19 Thread Nico Kadel-Garcia
On Thu, Jun 19, 2014 at 7:39 AM, George Dunlap dunl...@umich.edu wrote:
 On Wed, Jun 18, 2014 at 2:48 PM, Sven Kieske s.kie...@mittwald.de wrote:
 I just dived a little in virt-builder and here are my findings:

 1. It's awesome!

 Am 18.06.2014 12:46, schrieb George Dunlap:
 So it looks like we might want to recommend three potential paths we
 could recommend people to explore:

 1) For basic CentOS VMs, use a CentOS-provided cloud image, with our
 custom metadata tweaking script.

 2. Why create a custom script if maybe virt-builder can handle it?
I don't know if you can point virt-builder to other images than
 those on libguestfs.org, but this should be possible, include an centos
 cloud-image on libguestfs.org and just use virt-builder

 You can point virt-builder to another repo; and in fact, the guys on
 the libguestfs development list said that them hosting their own
 template repo was meant to be a temporary measure, and that long-term
 they'd like to see distros hosting their own templates.

 But as to why, did you miss that yum install libguestfs wants to
 bring in an *additional* 178 packages, more than doubling the size of
 a base installation? :-)

Building stripped OS images is an art form. In fact, if you want to
get *really* dirty, don't use disk images. Use a local chroot cage to
install an OS image from an initial minimal tarball, and use tools
like kickstart to pre-partition the disk and run theset steps..

1) Configure disk.
 a( Use parted in CentOS 6, or fdisk in CentOS 5 to pre-align
partitions on the 4096 byte block boundaries. All VM's that might run
on NetApp or other 4096 byte block drive back end storage needs this,
and better safe than sorry.
2) Obtain tarball, for example by downloading it into the swap
partition if your installer doesn't have a local copy on a DVD image
or local NFS share.
3) Configure /etc/fstab in the chroot cage. (Don't even put one in the
tarball, it's not needed!)
4) Configure /etc/syscontig/network-scripts/ifcfg-eth0 in the tarball,
as needed, for network layout.
a) Pay attention to /etc/udev.d/rules/70-persistent-net-rules,
which will reset your network device numbering.
b) It's usually safest to just delete it for VM and server images.
5) Run grub-install for the relevant bood disk, from inside the
chroot cage, to make it bootable.
6: Clear the installation tarball and run mkswap on the swap partition.

I don't know why most VM environments don't use a separate disk image
for swap, anyway, burying it inside your LVM setup makes it much more
onerous to efficiently cut free or resize without disturbing the rest
of your system. And it makes a thin-provisioned disk automatically
much bulkier, instead just leave out swap from published OS disk
images. But that's a very separate issue.

Now, when I first did this sort of thing, it was to shrink a corporate
Red Hat 5.2 build onto an installable CD. (Not RHEL. .2 Red Hat 5.2)
The original engineer had been using dd'd and gzipped disk images, of
different sizes for different disk drives, and trying to put them on
the same CD, and always starting over by zeroing the disk and putting
new images on it to make any changes, then dd'ing and re-compressing
the disk image. Including *swap*!  The same sort of wasted disk,
written but uncleared blocks, swap space, and other issues exist for
VM images, and a lot of the resulting image size is entirely unneeded
for OS installations. Getting the original OS image tarball can be
pesky: I had to install an OS, reboot with a rescue CD, and tarball
the contents of the disk partitions. I got it down so small it fit on
a buisness card CD.

But these days, guess what? mock already does most of this work for
me!!! Take a good look at the stored initialization tarballs for
mock, and they have *exactly* this sort of content. They have some
extra components for RPM building, but you can enter the chroot cage
and strip those right out, along with unnecessary log files, by
staying at run level 1 while in the tarball. I applaud the mock
authors for their work creating well defined workable chroot cages,
and take other advantage of them for testing components.

The initial setup takes some knowledge, and it's no longer just plug
in this disk image and be done, you need a working tool like a PXE
environment and a selection of pre-configured kickstart files with
'%pre scripts, or an installer CD or DVD or USB image with a
kickstart script set up, to make it efficient But it scales *really
well*. I helped do 13,000 systems in one month this way, back in 2002,
and the technique has proven invaluable for prototyping new,
completely defined, completely reviewable OS images ever since.
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-18 Thread Sven Kieske


Am 17.06.2014 19:31, schrieb lee:
 How about some sort of package management that lets you define and
 configure the VM?
 
 This is currently done from the inside, i. e. when the VM is running,
 with whatever installer and package manager a distribution comes
 with.
 
 Why not do it from the outside, i. e. before the VM even exists,
 creating it in the process?  Define some sort of API so that the same
 VM creator tool could be used with different distributions.

I believe you are talking about a bootstrapped minimal installation
and than managing this via a config management tool like puppet, chef
etc. ?

Nevertheless I think this gets really off topic and out of scope.

-- 
Mit freundlichen Grüßen / Regards

Sven Kieske

Systemadministrator
Mittwald CM Service GmbH  Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-18 Thread George Dunlap
On Mon, Jun 16, 2014 at 11:54 AM, Karanbir Singh mail-li...@karan.org wrote:
 On 06/10/2014 05:21 PM, Lars Kurth wrote:
 == #4 Cloud Image from Cloud Image SIG ==
 We could rely on pre-built cloud images from the Cloud Images SIG.
 People could just download the cloud image once it's done and customize
 it, rather than installing / building their own.

 Advantages: seems easy

 Disadvantages: coordination with Cloud Images SIG. May not be flexible
 enough

 We ship a test/devel grade CentOS-6-x86_64-pv image ( well, its a qcow2
 image, should work for pvhvm as well, the fstab is label driven ).[1]

 The biggest problem in doing pre-baked images is the instance metadata.
 We need to find an easy way to get network settings into the instance
 and the root password ( or key ), and finally - in some cases, console
 redirection/setup, but i dont think the console is a deal breaker or a
 big deal. The network and access credentials however are.

 In a typical cloud environ this info would come from the cloud
 controller's metadata service; on a typical virtualised setup though
 this becomes an issue ( and isnt really Xen specific ).

A couple of notes on virt-builder:

* When I tried it, all of the images booted on Xen out-of-the-box
except Fedora 19 and 20; I reported this to the list and the
developers were very responsive, so now everything works.  (The
exception might be RHEL7-rc, but I think should be gone now.)
* However, libguestfs has a massive dependency tree in RHEL7 for some
reason; KB said that a yum install libguestfs wanted to install 178
additional RPMs.  A minimal C6 install is only 143 RPMs, so this more
than doubles it.  That makes this a bit less desirable as the primary
method of getting a system up and running quickly.

So it looks like we might want to recommend three potential paths we
could recommend people to explore:

1) For basic CentOS VMs, use a CentOS-provided cloud image, with our
custom metadata tweaking script.

2) For more versatile image set-up and manipulation (including other
operating systems), use virt-builder.

3) If you're thinking about using libvirt anyway, use virt-install and
install from installation media.

Does that sound reasonable?

#1 still has some issues we need to work out -- particularly with
sorting out the metadata.  I'll start a separate thread to talk about
that.

 -George
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-18 Thread Sven Kieske
I just dived a little in virt-builder and here are my findings:

1. It's awesome!

Am 18.06.2014 12:46, schrieb George Dunlap:
 So it looks like we might want to recommend three potential paths we
 could recommend people to explore:
 
 1) For basic CentOS VMs, use a CentOS-provided cloud image, with our
 custom metadata tweaking script.

2. Why create a custom script if maybe virt-builder can handle it?
   I don't know if you can point virt-builder to other images than
those on libguestfs.org, but this should be possible, include an centos
cloud-image on libguestfs.org and just use virt-builder


 2) For more versatile image set-up and manipulation (including other
 operating systems), use virt-builder.
 
 3) If you're thinking about using libvirt anyway, use virt-install and
 install from installation media.

3. as a fallback if virt-builder is not available or you don't got
the images from libguestfs.org cached or you don't have direct internet
access: ok, for other purposes I guess virt-builder should be enough?

 Does that sound reasonable?

-- 
Mit freundlichen Grüßen / Regards

Sven Kieske

Systemadministrator
Mittwald CM Service GmbH  Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-18 Thread lee
Sven Kieske s.kie...@mittwald.de writes:

 Am 17.06.2014 19:31, schrieb lee:
 How about some sort of package management that lets you define and
 configure the VM?
 
 This is currently done from the inside, i. e. when the VM is running,
 with whatever installer and package manager a distribution comes
 with.
 
 Why not do it from the outside, i. e. before the VM even exists,
 creating it in the process?  Define some sort of API so that the same
 VM creator tool could be used with different distributions.

 I believe you are talking about a bootstrapped minimal installation
 and than managing this via a config management tool like puppet, chef
 etc. ?

No, I'm talking about an installer which can be used to create and to
configure a VM image.  The resulting VM image would have all needed
packages installed and be fully configured.

 Nevertheless I think this gets really off topic and out of scope.

Does provisioning VM images not involve their creation?


-- 
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-17 Thread lee
Karanbir Singh mail-li...@karan.org writes:

 On 06/10/2014 05:21 PM, Lars Kurth wrote:
 == #4 Cloud Image from Cloud Image SIG ==
 We could rely on pre-built cloud images from the Cloud Images SIG. 
 People could just download the cloud image once it's done and customize 
 it, rather than installing / building their own.
 
 Advantages: seems easy
 
 Disadvantages: coordination with Cloud Images SIG. May not be flexible 
 enough

 We ship a test/devel grade CentOS-6-x86_64-pv image ( well, its a qcow2
 image, should work for pvhvm as well, the fstab is label driven ).[1]

 The biggest problem in doing pre-baked images is the instance metadata.
 We need to find an easy way to get network settings into the instance
 and the root password ( or key ), and finally - in some cases, console
 redirection/setup, but i dont think the console is a deal breaker or a
 big deal. The network and access credentials however are.

 In a typical cloud environ this info would come from the cloud
 controller's metadata service; on a typical virtualised setup though
 this becomes an issue ( and isnt really Xen specific ).

 We could work around this by making some assumptions, we could 'own'
 dnsmasq and ensure that either libvirt is running and doing dhcp,
 otherwise we do the dhcp with some sane defaults, or we setup a script
 to 'instantiate image', which asks how the user wants to setup the
 instance ( pvhvm, hvm, pv ), the root password or key to use, and the
 network settings ( and if this is run on the dom0, we could even ask
 what bridge or device to connect with as well as the settings ).[2]

 Ofcourse, having these images pushed from here mean that clouds or
 virtualised environs that have metadata services are able to just-use
 the image as is, not needing any more tooling etc. And we can easily
 push monthly image updates and when things like heartbleed come around,
 there is a single place we need to update.

Wouldn't you still need to configure the services running in each VM?


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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-17 Thread George Dunlap
On Mon, Jun 16, 2014 at 11:54 AM, Karanbir Singh mail-li...@karan.org wrote:
 On 06/10/2014 05:21 PM, Lars Kurth wrote:
 == #4 Cloud Image from Cloud Image SIG ==
 We could rely on pre-built cloud images from the Cloud Images SIG.
 People could just download the cloud image once it's done and customize
 it, rather than installing / building their own.

 Advantages: seems easy

 Disadvantages: coordination with Cloud Images SIG. May not be flexible
 enough

 We ship a test/devel grade CentOS-6-x86_64-pv image ( well, its a qcow2
 image, should work for pvhvm as well, the fstab is label driven ).[1]

 The biggest problem in doing pre-baked images is the instance metadata.
 We need to find an easy way to get network settings into the instance
 and the root password ( or key ), and finally - in some cases, console
 redirection/setup, but i dont think the console is a deal breaker or a
 big deal. The network and access credentials however are.

 In a typical cloud environ this info would come from the cloud
 controller's metadata service; on a typical virtualised setup though
 this becomes an issue ( and isnt really Xen specific ).

 We could work around this by making some assumptions, we could 'own'
 dnsmasq and ensure that either libvirt is running and doing dhcp,
 otherwise we do the dhcp with some sane defaults, or we setup a script
 to 'instantiate image', which asks how the user wants to setup the
 instance ( pvhvm, hvm, pv ), the root password or key to use, and the
 network settings ( and if this is run on the dom0, we could even ask
 what bridge or device to connect with as well as the settings ).[2]

 Ofcourse, having these images pushed from here mean that clouds or
 virtualised environs that have metadata services are able to just-use
 the image as is, not needing any more tooling etc. And we can easily
 push monthly image updates and when things like heartbleed come around,
 there is a single place we need to update.

 - KB
 [1]: http://cloud.centos.org/centos/6/devel/

 [2] might need to pull in all of libguestfs to make the changes, which
 in turn has its own challenges if run inside a virtualised environ.

I didn't follow this -- virt-builder seems to run fine in dom0 with
qemu, albeit a bit slow.  Upstream is open to having patches for Xen
bindings for the utility VM.

Or is there something else I'm missing?

 -George
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-17 Thread lee
SilverTip257 silvertip...@gmail.com writes:

 On Tue, Jun 17, 2014 at 6:11 AM, lee l...@yun.yagibdah.de wrote:

 Karanbir Singh mail-li...@karan.org writes:

  Ofcourse, having these images pushed from here mean that clouds or
  virtualised environs that have metadata services are able to just-use
  the image as is, not needing any more tooling etc. And we can easily
  push monthly image updates and when things like heartbleed come around,
  there is a single place we need to update.

 Wouldn't you still need to configure the services running in each VM?


 Yes.

 I believe the idea here is to pre-configure as much as possible and
 complete the remaining configuration via network connectivity (ie: SSH).

How about some sort of package management that lets you define and
configure the VM?

This is currently done from the inside, i. e. when the VM is running,
with whatever installer and package manager a distribution comes
with.

Why not do it from the outside, i. e. before the VM even exists,
creating it in the process?  Define some sort of API so that the same
VM creator tool could be used with different distributions.


-- 
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-16 Thread Karanbir Singh
On 06/10/2014 05:21 PM, Lars Kurth wrote:
 == #4 Cloud Image from Cloud Image SIG ==
 We could rely on pre-built cloud images from the Cloud Images SIG. 
 People could just download the cloud image once it's done and customize 
 it, rather than installing / building their own.
 
 Advantages: seems easy
 
 Disadvantages: coordination with Cloud Images SIG. May not be flexible 
 enough

We ship a test/devel grade CentOS-6-x86_64-pv image ( well, its a qcow2
image, should work for pvhvm as well, the fstab is label driven ).[1]

The biggest problem in doing pre-baked images is the instance metadata.
We need to find an easy way to get network settings into the instance
and the root password ( or key ), and finally - in some cases, console
redirection/setup, but i dont think the console is a deal breaker or a
big deal. The network and access credentials however are.

In a typical cloud environ this info would come from the cloud
controller's metadata service; on a typical virtualised setup though
this becomes an issue ( and isnt really Xen specific ).

We could work around this by making some assumptions, we could 'own'
dnsmasq and ensure that either libvirt is running and doing dhcp,
otherwise we do the dhcp with some sane defaults, or we setup a script
to 'instantiate image', which asks how the user wants to setup the
instance ( pvhvm, hvm, pv ), the root password or key to use, and the
network settings ( and if this is run on the dom0, we could even ask
what bridge or device to connect with as well as the settings ).[2]

Ofcourse, having these images pushed from here mean that clouds or
virtualised environs that have metadata services are able to just-use
the image as is, not needing any more tooling etc. And we can easily
push monthly image updates and when things like heartbleed come around,
there is a single place we need to update.

- KB
[1]: http://cloud.centos.org/centos/6/devel/

[2] might need to pull in all of libguestfs to make the changes, which
in turn has its own challenges if run inside a virtualised environ.

-- 
Karanbir Singh
+44-207-0999389 | http://www.karan.org/ | twitter.com/kbsingh
GnuPG Key : http://www.karan.org/publickey.asc
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-13 Thread lee
Dario Faggioli raist...@linux.it writes:

 On gio, 2014-06-12 at 07:17 +0200, lee wrote:
 Lars Kurth lars.ku...@xen.org writes:

 Let me wear the hat of the user.  The major hurdles were network setup,
 installing something in a vm, and the chaotic state the documentation is
 in.
 
 Wow... chaotic state :-O

 Don't get me wrong. I know everything can always be improved, and
 documentation is --for free software in general, which well includes
 Xen-- often in a position of needing _a_lot_ of improvement.

 All that being said, it would be helpful if you could be a bit more
 specific and help us actually improve it.

It's really difficult to be any specific because I have to piece
together information from whatever sources are available through search
engines and by trial and error.

Perhaps take practical questions and try to answer them from the
documentation you can find, for example:


I have an installer for distribution X.  How do I install the
distribution in a VM?

How do I make sure that a particular network interface I have in dom0
will always show up as a particular network interface in domU?

What is an xvda device, what are the impacts of using one instead of,
for example, /dev/sda, and how are the devices named when I have several
of them because after installing a VM, I want to give it access to
another logical volume: xvda1, xvda2, etc., or xvdb, xvdc, or something
else?

Why does it say I need more memory ... when trying to create a guest
with xm?  Can't I do memory overcommittment?  My dom0 has plenty of swap
space.

What are the effects of overcommitting CPUs?  Should I rather limit the
VMs tightly or give them CPUs so that they can be used as needed instead
of being left idle?

Do I need to load a particular module in a VM to be able to give it more
memory with xm?  What happens when I give a VM more memory and then take
it away after a while?

How do I make it so that memory is assigned to VMs dynamically up to
their maximum allowed amounts, depending on how much memory a VM
currently happens to need?

Why gives xenpm get-cpufreq-states no output?

Why do I get an entry (XEN) physdev.c:168: dom0: wrong map_pirq type 3
in xm dmesg, and what is it supposed to tell me?


When you assume you're new to using xen and try to answer questions like
this from whatever documentation you can find, you'll probably see what
I mean :)

 I think you've said, in another thread, that you requested editor
 access to the wiki, but don't know what status such request is in
 (provided I'm not mistaking you with someone else, in which case,
 sorry! :-P). Can you double check, so that we can see how to move
 forward and allow you to act instead of only complaining. :-D

I think the request has been successful.  I'm still working on getting
everything set up and didn't get to look into editing the wiki yet.

 As a user, I'm used to get an ISO of an installer or of a life system,
 put that into a DVD drive or write it to an USB stick and to boot from
 that to do the installation.  Why can't I do that with xen?
 
 Wait, what? Who said you can't do it? Of course you can! In fact, if you
 tried and it failed, please, report the bug within the appropriate
 channel, because a bug is what that is, nothing less! :-O

Well, how do you do that?  IIRC, I followed
http://wiki.xen.org/wiki/Debian_Guest_Installation_Using_Debian_Installer,
and it installs squeeze instead of wheezy.  Apparently you require a
special kernel and initrd.img to install something in a VM --- so how do
you install something else?

 However, I think we're talking about something different here...

  == #1 virt-install ==
  == #2 xen-tools ==
  == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
  == #4 Cloud Image from Cloud Image SIG ==
 
 I wouldn't want #4.  I want to be able to just use the installer of
 whatever distribution I'm installing in a VM and a simple way of saying
 run this in a VM and let me install.  Or perhaps I merely want to run
 a life system in a VM to try it out, with network access.  What easy way
 is there to do that?
 
 I'm not sure I got what you mean with 'I merely want to run
  a life system in a VM to try it out'. If you mean trying out Xen in a
 VM, then of course you need a nested-virt capable platform.

No, I was assuming that I have a dom0 running and decide, for example,
that I want to try out the live DVD of some Fedora spin in another VM.

 If you have one, here's the instructions of how to create a Xen
 liveCD. I'm afraid both the instructions and the liveCD are Fedora
 based, but it should not be a big deal to bias them toward CentOS:

 http://lists.xen.org/archives/html/xen-users/2014-06/msg00065.html

Oh I've seen this page --- it wasn't was I was looking for, though.

 I also don't know much of #3, but at least #1 and #2, are both meant
 at doing exactly what you're saying: install this in a VM, they only
 happen not to require install DVDs. I understand that DVDs are your
 preferred method, 

Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On gio, 2014-06-12 at 07:17 +0200, lee wrote:
 Lars Kurth lars.ku...@xen.org writes:

 Let me wear the hat of the user.  The major hurdles were network setup,
 installing something in a vm, and the chaotic state the documentation is
 in.
 
Wow... chaotic state :-O

Don't get me wrong. I know everything can always be improved, and
documentation is --for free software in general, which well includes
Xen-- often in a position of needing _a_lot_ of improvement.

All that being said, it would be helpful if you could be a bit more
specific and help us actually improve it. I think you've said, in
another thread, that you requested editor access to the wiki, but don't
know what status such request is in (provided I'm not mistaking you with
someone else, in which case, sorry! :-P). Can you double check, so that
we can see how to move forward and allow you to act instead of only
complaining. :-D

 As a user, I'm used to get an ISO of an installer or of a life system,
 put that into a DVD drive or write it to an USB stick and to boot from
 that to do the installation.  Why can't I do that with xen?
 
Wait, what? Who said you can't do it? Of course you can! In fact, if you
tried and it failed, please, report the bug within the appropriate
channel, because a bug is what that is, nothing less! :-O

However, I think we're talking about something different here...

  == #1 virt-install ==
  == #2 xen-tools ==
  == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
  == #4 Cloud Image from Cloud Image SIG ==
 
 I wouldn't want #4.  I want to be able to just use the installer of
 whatever distribution I'm installing in a VM and a simple way of saying
 run this in a VM and let me install.  Or perhaps I merely want to run
 a life system in a VM to try it out, with network access.  What easy way
 is there to do that?
 
I'm not sure I got what you mean with 'I merely want to run
 a life system in a VM to try it out'. If you mean trying out Xen in a
VM, then of course you need a nested-virt capable platform. If you have
one, here's the instructions of how to create a Xen liveCD. I'm afraid
both the instructions and the liveCD are Fedora based, but it should not
be a big deal to bias them toward CentOS:

http://lists.xen.org/archives/html/xen-users/2014-06/msg00065.html

I also don't know much of #3, but at least #1 and #2, are both meant at
doing exactly what you're saying: install this in a VM, they only
happen not to require install DVDs. I understand that DVDs are your
preferred method, but that doesn't make it the one _everyone_ prefer!

AFAIUI, when talking about this kind of provisioning, what we're
interested is something a lot more automated and, as a consequence, a
lot less interactive than an installer.

 For example: http://wiki.xen.org/wiki/Credit_Scheduler:
 
Ok, now we're talking! That's what I meant when asking to 'be
specific'! :-)

 It is now the default scheduler in the xen-unstable trunk.
 
 So is it the default in the version I'm using or what?
 
Good point, I'll fix this.

 The SEDF and BVT schedulers are still optionally available but the plan
 of record is for them to be phased out and eventually removed.

 What are those and have they been removed in the version I'm using?

Ditto.

 Schedule Rate Limiting (added in Xen 4.2)
 
 That doesn't belong there.  It needs to go into the documentation for
 that particular version of xen.
 
 Timeslice (added in Xen 4.2)
 [...]
 # xl sched-credit -t [n]
 
 dito
 
I don't agree. I think they do belnog. Of course, that does not mean we
can't link to them from a 'Xen 4.2' page.

 I always admire the documentation exim has ...  As to your original
 question:
 
  I was wondering whether we need to look at a standard way in which we
  recommend how to provision images for VMs.
 
 I'd suggest to start with splitting the documentation into different
 versions, one version of documentation for each version of xen.  Some
 way to get a VM running may then be discovered and improved upon.
 
Personally, I don't think that would be the optimal split, or something
we need to do right now (which does not mean we should not improve docs
in other ways). However, I think you're way off the 'original question'
which, again, was about provisioning.

Regards,
Dario

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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
On 06/12/2014 05:17 PM, lee wrote:
 I knew before I started that network setup would be a PITA because years
 ago, I set up a VM for someone who didn't have a 64bit system to compile
 a 64bit version of some software.  The network setup being so
 ridiculously difficult has kept me from touching VMs ever again for
 years.  It's just too difficult and not worth the effort unless you're
 really forced to do it.

Networking can be confusing until it clicks then it all seems to fall
into place, there is a certain amount of understanding of the overall
picture of how bridge networking (or other types of networking) works
that once you get that understanding it becomes a lot simpler.  One
thing that probably confuses you is that there are certain parts of the
networking that are done by the dom0 distro, certain parts are done by
Xen scripts and front and backend drivers, and some parts are done by
the domu operating system.  Understanding how those parts fit together
and how different distros do the same thing but perhaps with different
configs helps a lot to getting a grasp on the whole.

Obviously better documentation would help with this, but like anything
of this nature there is a learning curve that you simply have to get
over before you can really become proficient.

 As a user, I'm used to get an ISO of an installer or of a life system,
 put that into a DVD drive or write it to an USB stick and to boot from
 that to do the installation.  Why can't I do that with xen?

You can do that with Xen, KVM, and most other types of virtualization.
The idea is that you need to block-attach the disk (or ISO file if you
prefer not to use a physical disk) to the VM and then it can be mounted
and used as install media (or any other type of media for that matter).
 This can be done from teh domain config file or from the xm (or xl)
command line.

Another quick note specifically for you.  I have noticed in past
messages that you seem to be having some confusion with xm vs xl
commands and some explanation about that is probably in order to clear
up that confusion.  xm and xl are nearly identical commands to use, but
xm is the old way and xl the new way.  Basically put, xm interfaces
with a daemon running in the dom0 (xend) which in turn interfaces with
the hypervisor, while xl uses libraries to interface directly with the
hypervisor and so eliminates the need for xend.  You will see
documentation refer to one or the other, sometimes almost
interchangeably, because the two tools have almost identical usage, but
what you should be aware of is that you really need to pick one and
stick with it, Xen does not work well if you try to use xm for some
commands and xl for others.  Since you're new I would recommend xl
because xm is deprecated in newer versions of Xen, so if you want to
future-proof your knowledge xl is the way to go.  Also if you're using
xl then you should not be running the xend daemon, this is easily
accomplished by using chkconfig and service to turn xend off.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
On 06/11/2014 04:21 AM, Lars Kurth wrote:
 Hi all,
 
 following the discussion on about documentation, I was wondering whether 
 we need to look at a standard way in which we recommend how to provision 
 images for VMs. Am starting this with a Xen hat, but the discussion 
 should not be specific to this. There are a number of options, but all 
 have some trade-offs
 
 == #1 virt-install ==
 == #2 xen-tools ==
 == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
 == #4 Cloud Image from Cloud Image SIG ==

This is not a complete list of the ways you can install a VM either.  My
personal preference is to manually create the filesystem for the VM and
then install the OS core with yum.  Then after tweaking some config
files you can start up the VM and finish installing whatever else you
want with yum as well.

While I don't think that this should be the recommended install method
it might be worth mentioning and even giving a wiki page with some
instructions on how to do it this way.  Doing an install like this is
actually very good for a newbie because you get your hands dirty and
get a really good understanding of how yum works and the internals of
the distro.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On mar, 2014-06-10 at 17:21 +0100, Lars Kurth wrote:
 Hi all,
 
Hi!

 == #1 virt-install ==
 
 Advantages: similar to KVM
 
 Disadvantages: may cause weird issues / confusion with people switching 
 back to xl. The core issue is that with the current version of xen and 
 libvirt, this only works with xm (when xl is used, this can create some 
 undefined behavior). However as we have seen in some recent threads on 
 this list, people tend to mix which can cause problems.
 
When you're saying this only works with xm (when xl is used, this can
create some undefined behavior, that is because of the particular
version of libvirt (and Xen) is available in CentOS?

I'm asking because, with current enough versions of both, situation
should not be that bad, at least not as far as virt-install and VM
provisioning are concerned... :-O

Personally, I'm not sure whether this is the best solution, but I see it
like something that should not be left in a 'non-working' state.

Parhaps, a disadvantage I see in going for it as the default and
recommended mechanism is that you really need:
 - a recent version of libvit to start with
 - a way to update libvirt quite often, to take advantage of new 
   features being added

 == #2 xen-tools ==
 
 Advantages: Very flexible. Many other distros use xen-tools, so we have 
 lots of beginners docs that just need to be tweaked
 
 Disadvantages: needs porting/packaging for CentOS. Does not work for 
 kvm. Says xen. (Maybe that's an advantage.)
 We know that xen-tools works with Fedora (see 
 http://blog.xen.org/index.php/2013/01/24/using-xen-tools-on-fedora/), so 
 the porting effort may be small
 
Yep, and I went beyond that, and produced some spec files. This should
be the latest one, although it's for version 4.3.1 of xen-tools, so no,
not the latest possible or the tip of the repo:
http://dariof.fedorapeople.org/SPECS/xen-tools.spec

My main problem with xen-tools is that it is kind of debian (and
derivatives) biased, when it comes to building the guest file system.
I.e., last time I tried, provisioning a Fedora or CentOS guest was
possible, but not as straightforward as creating a debian one. That is
not xen-tool's fault, is the fact there were no good alternatives to
debootstrap.

However, it looks like rinse (one of said alternatives to debootstrap)
is getting some steam again:
https://gitorious.org/rinse

so that may actually be worth a try.

Also, I recently saw this in xen-tools-discuss mailing list:

anouncement : Xen-tools update for centos 6.5
 http://xen-tools.org/pipermail/xen-tools-discuss/2014-May/001053.html

Even if only for the title, it looks like something to investigate! :-P

 Unknowns: What would be needed to make it work for CentOS
 
Talking a bit with Axel (xen-tools' maintainer) at the time, the main
issue in packaging subsequent versions of xen-tools for Fedora was going
to be some dependencies from a bunch of perl module he wrote, and
packaged himself for Debian, as separate packages. Nothing terrible, but
that would mean making the RPMs for those modules as well.

TBH, it is a while back, and I'm not sure what happened, whether went
that route. This link, from the xen-tools-discuss email mentioned above:
https://github.com/remsnet/xen-tools-rpmbuild

seems to have (more) updated spec files. I haven't tried them, though.

 == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
 
 Advantages: supports KVM, Xen and other VM inages. Seems easy to use.
 - if so, it would avoid xm / xl confusion.
 
 Unknowns: Not sure at which level virt-builder integrates with Xen and 
 other hypervisors. It seems to operate at disk image format (similar to 
 xen-tools) . I don't know whether virt-builder is restricted to some 
 hypervisors in RHEL7.
 
 Disadvantages: may need porting/packaging for CentOS. It appears as if 
 it will be in RHEL7, so it may just appear with CentOS 7. If not, some 
 porting work may need to be done.
 
Not commenting on this as I don't know it.

All that being said, and FWIW, I think I'd prefer #1, provided a recent
enough version of Xen and Libvirt could be used.

Regards,
Dario

-- 
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-
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Dario Faggioli
On gio, 2014-06-12 at 22:34 +1200, Peter wrote:
 This is not a complete list of the ways you can install a VM either.  My
 personal preference is to manually create the filesystem for the VM and
 then install the OS core with yum.  Then after tweaking some config
 files you can start up the VM and finish installing whatever else you
 want with yum as well.
 
 While I don't think that this should be the recommended install method
 it might be worth mentioning and even giving a wiki page with some
 instructions on how to do it this way.  Doing an install like this is
 actually very good for a newbie because you get your hands dirty and
 get a really good understanding of how yum works and the internals of
 the distro.
 
Indeed it does!

If you're up for it, Xen wiki will be glad to host it! :-P

We've got both CentOS and Fedora categories on the Wiki, both hosting
various pages, guides, instructions, etc., but none of them (I think)
goes through the procedure you mentioned:

http://wiki.xen.org/wiki/Category:CentOS
http://wiki.xen.org/wiki/Category:Fedora

Feel free to add it! :-)

Regards,
Dario

-- 
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-
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Ed Heron
On Tue, 2014-06-10 at 17:21 +0100, Lars Kurth wrote:
 Hi all,
 
 following the discussion on about documentation, I was wondering whether 
 we need to look at a standard way in which we recommend how to provision 
 images for VMs. Am starting this with a Xen hat, but the discussion 
 should not be specific to this. There are a number of options, but all 
 have some trade-offs
 
 == #1 virt-install ==
 
 Advantages: similar to KVM
 
 Disadvantages: may cause weird issues / confusion with people switching 
 back to xl. The core issue is that with the current version of xen and 
 libvirt, this only works with xm (when xl is used, this can create some 
 undefined behavior). However as we have seen in some recent threads on 
 this list, people tend to mix which can cause problems.
 ...

  I've chosen the virt-install method on CentOS 5 precisely because it
is like KVM.  I was hoping it would fulfill the promise of being
hypervisor agnostic.  I'm hoping it continues to be available on future
versions of CentOS with Xen.

  Though it is a waste of resources, I make all my virtual machines,
Linux and MS Windows alike, fully virtualized.  I can then move any of
the VM's with the same virt-install --import or virsh dumpxml/edit/virsh
define process.

  When moving a VM, usually the only thing I have to do outside of
virt-install/virt-manager is add acpi/, apic/ or pae/, which can
be done with virsh edit.  I don't know why some of my virtual servers
need them and other don't but I have higher priority things to think
about.

  I'm the only technical support person and I don't work 24/7.  The
graphical interface of virt-manager makes it possible for non-tech
people to see what is running and see consoles to restart any
misbehaving VM's (usually MS Windows VM's).

  I have completely eliminated my use of xm.


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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread SilverTip257
On Thu, Jun 12, 2014 at 11:47 AM, Dario Faggioli raist...@linux.it wrote:

 On gio, 2014-06-12 at 22:34 +1200, Peter wrote:
  This is not a complete list of the ways you can install a VM either.  My
  personal preference is to manually create the filesystem for the VM and
  then install the OS core with yum.  Then after tweaking some config
  files you can start up the VM and finish installing whatever else you
  want with yum as well.
 
  While I don't think that this should be the recommended install method
  it might be worth mentioning and even giving a wiki page with some
  instructions on how to do it this way.  Doing an install like this is
  actually very good for a newbie because you get your hands dirty and
  get a really good understanding of how yum works and the internals of
  the distro.


@Peter,
Would you mind sharing the process?
(on the CentOS or Xen wikis OR share a link to a write-up online?)

This piques my curiosity and I'd like to know more. ;-)
Thanks!


  
 Indeed it does!

 If you're up for it, Xen wiki will be glad to host it! :-P

 We've got both CentOS and Fedora categories on the Wiki, both hosting
 various pages, guides, instructions, etc., but none of them (I think)
 goes through the procedure you mentioned:

 http://wiki.xen.org/wiki/Category:CentOS
 http://wiki.xen.org/wiki/Category:Fedora

 Feel free to add it! :-)


+1 :-D



 Regards,
 Dario

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 -
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

On 06/13/2014 03:47 AM, Dario Faggioli wrote:
 If you're up for it, Xen wiki will be glad to host it! :-P

I would love to do a writeup on this, but my time is extremely limited
right now.  I'll see what I can do.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread Peter
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

On 06/13/2014 08:30 AM, Peter wrote:
 On 06/13/2014 03:47 AM, Dario Faggioli wrote:
 If you're up for it, Xen wiki will be glad to host it! :-P
 
 I would love to do a writeup on this, but my time is extremely
 limited right now.  I'll see what I can do.

Actually, what I'll probably do is wait for CentOS 7 to drop and then
do a writeup based on that.  I'll be wanting to set up a VM from it
anyways and so then I'll kill two birds with one stone.


Peter
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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-12 Thread NightLightHosts Admin
The world needs documentation bounties.


On Thu, Jun 12, 2014 at 4:30 PM, Peter pe...@pajamian.dhs.org wrote:

 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA1

 On 06/13/2014 03:47 AM, Dario Faggioli wrote:
  If you're up for it, Xen wiki will be glad to host it! :-P

 I would love to do a writeup on this, but my time is extremely limited
 right now.  I'll see what I can do.


 Peter
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 Version: GnuPG v1
 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

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Re: [CentOS-virt] Preferred method of provisioning VM images

2014-06-11 Thread lee
Lars Kurth lars.ku...@xen.org writes:

 Hi all,

 following the discussion on about documentation, I was wondering whether 
 we need to look at a standard way in which we recommend how to provision 
 images for VMs. Am starting this with a Xen hat, but the discussion 
 should not be specific to this. There are a number of options, but all 
 have some trade-offs

Let me wear the hat of the user.  The major hurdles were network setup,
installing something in a vm, and the chaotic state the documentation is
in.

I knew before I started that network setup would be a PITA because years
ago, I set up a VM for someone who didn't have a 64bit system to compile
a 64bit version of some software.  The network setup being so
ridiculously difficult has kept me from touching VMs ever again for
years.  It's just too difficult and not worth the effort unless you're
really forced to do it.

As a user, I'm used to get an ISO of an installer or of a life system,
put that into a DVD drive or write it to an USB stick and to boot from
that to do the installation.  Why can't I do that with xen?


 == #1 virt-install ==
 == #2 xen-tools ==
 == #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==
 == #4 Cloud Image from Cloud Image SIG ==

I wouldn't want #4.  I want to be able to just use the installer of
whatever distribution I'm installing in a VM and a simple way of saying
run this in a VM and let me install.  Or perhaps I merely want to run
a life system in a VM to try it out, with network access.  What easy way
is there to do that?

I haven't heared of #3.

#2 and #1 lead to total confusion.  Xen doesn't have any way to use an
installer ISO to install a VM.  The documentation is confusing because
it lacks clarity and refers to many versions of xen at the same time
which suggest to do things differently so that you don't know how you
are supposed to do something.  There is no documentation for centos
about how to set up a VM.

#2 and #1 use different ways and different formats of configuration
files, and apparently #1 doesn't support everything #2 does and brings
about an undesirable overhead while apparently being a good choice for
users who also use other things than xen and don't want to learn
different ways of managing VMs.

When I use xen, I do not need #1, and it seems to make more sense to me
to stick with #2.

#2 needs clarity of documentation.  I've got an installer ISO.  The
documentation needs to tell me straightforwardly what I need to do to
get a VM running with this installer ISO.  I don't care about #1--4 at
that point.

It's that simple.  More details can be learned over time.


Insofar the documentation needs to deal with different versions of xen,
just split the documentation entirely.  When I use version X, I do not
want to read the documentation for versions A, B, C or Z.  That's
confusing and I have to ask myself all the time which part of what I'm
reading might apply to the software I'm using, and that makes reading
the documentation very painful.

It's like you buy a new TV and it comes with 5 pages of
documentation because the manufacturer of the TV mentions everything for
every model of TV they ever manufactured, rather than documenting no
more than the TV you actually bought.  Trying to figure out how to
switch to a different channel or how to increase the volume takes at
least two days each.


For example: http://wiki.xen.org/wiki/Credit_Scheduler:

It is now the default scheduler in the xen-unstable trunk.

So is it the default in the version I'm using or what?

The SEDF and BVT schedulers are still optionally available but the plan
of record is for them to be phased out and eventually removed.

What are those and have they been removed in the version I'm using?  But
then, it probably doesn't matter what they are because they might have
been removed anyway.  So what is this information supposed to tell me??

A domain with a weight of 512 will get twice as much CPU as a domain
with a weight of 256 on a contended host. Legal weights range from 1 to
65535 and the default is 256.

Where would I change this default?  What happens when I set a weight of
100 or of 33?  I can only guess that it might be rounded up or down to
something like 128 or 64 or 32 or 64.  Or perhaps actually floating
point math is employed to compute the relations of the different
weights?  Probably not ...

Schedule Rate Limiting (added in Xen 4.2)

That doesn't belong there.  It needs to go into the documentation for
that particular version of xen.

Timeslice (added in Xen 4.2)
[...]
# xl sched-credit -t [n]

dito

Usage

The xm sched-credit command may be used to tune the per VM guest scheduler 
parameters.

So what am I supposed to use? xm or xl?  Or something else, maybe virsh?

I always admire the documentation exim has ...  As to your original
question:

 I was wondering whether we need to look at a standard way in which we
 recommend how to provision images for VMs.

I'd suggest to start with splitting the 

[CentOS-virt] Preferred method of provisioning VM images

2014-06-10 Thread Lars Kurth
Hi all,

following the discussion on about documentation, I was wondering whether 
we need to look at a standard way in which we recommend how to provision 
images for VMs. Am starting this with a Xen hat, but the discussion 
should not be specific to this. There are a number of options, but all 
have some trade-offs

== #1 virt-install ==

Advantages: similar to KVM

Disadvantages: may cause weird issues / confusion with people switching 
back to xl. The core issue is that with the current version of xen and 
libvirt, this only works with xm (when xl is used, this can create some 
undefined behavior). However as we have seen in some recent threads on 
this list, people tend to mix which can cause problems.

== #2 xen-tools ==

Advantages: Very flexible. Many other distros use xen-tools, so we have 
lots of beginners docs that just need to be tweaked

Disadvantages: needs porting/packaging for CentOS. Does not work for 
kvm. Says xen. (Maybe that's an advantage.)
We know that xen-tools works with Fedora (see 
http://blog.xen.org/index.php/2013/01/24/using-xen-tools-on-fedora/), so 
the porting effort may be small

Unknowns: What would be needed to make it work for CentOS

== #3 virt-builder (http://libguestfs.org/virt-builder.1.html) ==

Advantages: supports KVM, Xen and other VM inages. Seems easy to use.
- if so, it would avoid xm / xl confusion.

Unknowns: Not sure at which level virt-builder integrates with Xen and 
other hypervisors. It seems to operate at disk image format (similar to 
xen-tools) . I don't know whether virt-builder is restricted to some 
hypervisors in RHEL7.

Disadvantages: may need porting/packaging for CentOS. It appears as if 
it will be in RHEL7, so it may just appear with CentOS 7. If not, some 
porting work may need to be done.

== #4 Cloud Image from Cloud Image SIG ==
We could rely on pre-built cloud images from the Cloud Images SIG. 
People could just download the cloud image once it's done and customize 
it, rather than installing / building their own.

Advantages: seems easy

Disadvantages: coordination with Cloud Images SIG. May not be flexible 
enough

I just wanted to start a discussion about this and ask for input. This 
topic which has come up a number of times in SIG meetings as a facgtor 
influencing libvirt and other package versions.

Regards
Lars
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