[Users] Manage KVM/Qemu and OpenVZ the same way

Bosson VZ bossonvz at bosson.eu
Tue Jul 8 07:43:03 PDT 2014


Hello,

I know about the recent change in UB limits default settings in vzctl. I haven't implemented the same logic into bossonvz yet because 
I have had some problems with the mentioned change in vzctl on some of my testing containers in the past. I will return to the problem and fix it, it will be very simple.

About ploop: we don't use ploop on our clusters because we have a shared storage based on top of drbd. All container data is replicated to all cluster nodes and so during migration, we don't have to wait for the sync (be it ploop copy or scp). How long would the container migrate using the ploop copy if a container partition would be, let's say, 500 GiB?

We also try to keep the amount of storage layers as small as possible to gain maximum throughput. OCFS, clustered LVMs and drbd suit us quite well. You can extend or shrink LVMs online and extend fss online with ext4 at least.

You can transfer an LVM to a remote node online using pvmove and iscsi. We use it regularly without any trouble.

Online snapshot merging is not possible with LVMs, that is true.

I don't know if I like the fact that you had to patch ext4 to get the extra features of ploop. I wouldn't say that trading stability for functions is the best idea. We've had problems in the past with bugs in the modified vzkernel ext4 leading to broken production file systems.

-- 
David Fabian
Cluster Design, s.r.o.

Dne Čt 3. července 2014 11:13:19, Kir Kolyshkin napsal(a):
> On 07/03/2014 05:19 AM, Bosson VZ wrote:
> >
> > Hi,
> >
> >  
> >
> > the driver supports vSwap AFAIK. You can set RAM limits (soft, hard)
> > and SWAP hard limit (soft is always 0). Could you explain to me what
> > you mean by vRaw?
> >
> >  
> >
> > I understand that vzctl provides a lot of knobs to play with but since
> > libvirt is supposed to be a common management interface, I had to play
> > by the libvirt rules. I extended the libvirt XML syntax only as much
> > as was needed for supporting the amount of features that we use at the
> > company. I also didn't want break too many things and sticked with the
> > semantics that was already in libvirt for LXC.
> >
> >  
> >
> > UBC settings is currently reduces to only manage RAM and SWAP. All
> > other UBC limits are set as unrestricted.
> >
> 
> You'd better also set some secondary UBCs (if those are not set
> explicitly), same
> as vzctl does and as described at
> http://openvz.org/VSwap#Implicit_UBC_parameters
> 
> Those are lockedpages, oomguarpages, vmguarpages, and optionally
> privvmpages.
> 
> > Technically, it is not hard to extend the driver to support all the
> > UBC limits but I don't want to divert from the upstream libvirt domain
> > file syntax too much.
> >
> >  
> >
> > Ploop is not supported as we don't use it in the company. Most of the
> > features that ploop provides can be easily achieved with LVM/drbd.
> >
> 
> I tend to disagree here.
> 
> First, ploop works on top of ext4 filesystem, so it's way more flexible.
> You just can't move an LVM partition to a different server (in ploop
> case it's just scp).
> 
> There is no online snapshot merging in LVM as far as I know.
> 
> Finally, I can't see how DRBD can be a replacement for ploop copy.
> 
> This is just from the top of my head, maybe there's something else
> as well (say I'm not sure how good is LVM online grow/shrink).
> 
> > However, unlike the UBC limits, there is already a syntax for
> > "mounting a file as a file system" in libvirt, so implementing ploop
> > might be possible.
> >
> >  
> >
> >
> > David Fabian
> >
> > Cluster Design, s.r.o.
> >
> >  
> >
> > Dne St 2. c(ervence 2014 17:20:19, Pavel Odintsov napsal(a):
> >
> > > Hello!
> >
> > >
> >
> > > Very nice! But what about vRaw/vSwap/non standard UBC management and
> >
> > > ploop support? I'm used libvirt for kvm few years but it's really ugly
> >
> > > for OpenVZ in upstream repository from RH.
> >
> > >
> >
> > > On Wed, Jul 2, 2014 at 4:26 PM, Bosson VZ <bossonvz at bosson.eu> wrote:
> >
> > > > Helo,
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > for everyone who would like to manage their Qemu/KVM and OpenVZ
> > virtuals in
> >
> > > > the same fashion, I am presenting a new libvirt driver, bossonvz,
> > which will
> >
> > > > allow you to manage OpenVZ containers with libvirt. To name a
> > couple of
> >
> > > > features:
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > - complete control over the container
> >
> > > >
> >
> > > > - live migration via libvirtd
> >
> > > >
> >
> > > > - remote VNC console
> >
> > > >
> >
> > > > - fs mounts management
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > Just check this web page out to find out more.
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > http://bossonvz.bosson.eu/
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > The driver is provided as a separate patch to libvirt and as RPM
> > packages
> >
> > > > for CentOS/SL 6.5.
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > --
> >
> > > >
> >
> > > > David Fabian
> >
> > > >
> >
> > > > Cluster Design, s.r.o.
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > _______________________________________________
> >
> > > > Users mailing list
> >
> > > > Users at openvz.org
> >
> > > > https://lists.openvz.org/mailman/listinfo/users
> >
> > > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> >
> >
> > _______________________________________________
> > Users mailing list
> > Users at openvz.org
> > https://lists.openvz.org/mailman/listinfo/users
> 
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