Xen users - Jan 2013 - size units in xen-create-image, and other newbie doubts

Greetings,

I'm fiddling with Xen at home, the dom0 is a freshly installed Debian
stable (current 6.0.6 squeeze) using LVM over RAID.

I want to use two VGs, so the pointy-clicky won't really do since
--lvm only takes one argument (i assume). That's no big deal, i can
use LVM tools and even the partitions.d scripts xen-tools can use and
provide a partition template through the  --partitions flag.

However, the man page refers:

         size       = 2Gb      # Disk image size.
         image      = full     # Allocate the full disk size immediately.
         memory     = 128Mb    # Memory size
         swap       = 128Mb    # Swap size

These units are plain wrong, as they should be GB and MB. Regardless,
are these 128 for --swap MB or MiB? And what about --size?

In other news,

when specifying --gateway, what's recommended: dom0 or the gw dom0
uses? Or does it depend on what i want Xen for? What about
--nameserver? how about openvswitch? I intend to have a few PVs for
basic services like http, maybe nfs and samba, etcd, etcd; and maybe
one or two or five HVMs plus the PVM that'll server as my desktop. The
host is in a regular home LAN plugged into a crappy ISP router.

How can i know which --arch and --dist xen-create-image supports? I'm
assuming --arch=amd64 and
--dist={sid,unstable,squeeze,whezzy,testing}?

While the host sees /dev/mapper stuff and the md (RAID1), will the
domUs see LVM disks as xvds by default? Regardless of whether i create
them directly with LVM or using xen-create-image?

Sorry for all the questions, i'll glady take pointers to detailed
howtos and mans.

Eh, the hardware's an Asus M2NPV-VM motherboard with an Ahlon64, 8GiB
DDR2 RAM and two SATA drives, one 160GB and one 1TB. 159GB are RAIDed
and those and the remainder are LVMed into two VGs. There's an onboard
nvidia Geforce and a PCI ATI/Asus Radeon HD 50** (i'd like to
passthrough it to the desktop PV eventually).

There's a lot i want to do, i welcome any tips and constructive criticism.

TIA,
Nuno Magalhães

PS: sorry if this is the wrong list...

-- 
"On the internet, nobody knows you're a dog."

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Hello.

El 21/01/13 14:40, Nuno Magalhães escribió:
> Greetings,
>
> I'm fiddling with Xen at home, the dom0 is a freshly installed Debian
> stable (current 6.0.6 squeeze) using LVM over RAID.
>
> I want to use two VGs, so the pointy-clicky won't really do since
> --lvm only takes one argument (i assume). That's no big deal, i can
> use LVM tools and even the partitions.d scripts xen-tools can use and
> provide a partition template through the  --partitions flag.
The usage of partition template is very comfortable. Highly recommended.
> However, the man page refers:
>
>           size       = 2Gb      # Disk image size.
>           image      = full     # Allocate the full disk size immediately.
>           memory     = 128Mb    # Memory size
>           swap       = 128Mb    # Swap size
>
> These units are plain wrong, as they should be GB and MB. Regardless,
> are these 128 for --swap MB or MiB? And what about --size?
Being purist, I must agree, although the context hardly allows any 
confusion.
What's wrong with --size?
> when specifying --gateway, what's recommended: dom0 or the gw dom0
> uses? Or does it depend on what i want Xen for?
Yes, in entirely depend on your network topology.
In the most simple case, where your DomU has it's network interface in 
the same bridge, as Dom0, use the same gateway as your Dom0. Finally, 
consider that it will be the address configured ad "gateway" in 
/etc/network/interfaces of the guest machine.
> What about
> --nameserver?
Same thing.
> how about openvswitch?
NWM.
> I intend to have a few PVs for
> basic services like http, maybe nfs and samba, etcd, etcd; and maybe
> one or two or five HVMs plus the PVM that'll server as my desktop. The
> host is in a regular home LAN plugged into a crappy ISP router.
Seems quite standard, shall be no surprises.
> How can i know which --arch and --dist xen-create-image supports? I'm
> assuming --arch=amd64 and
> --dist={sid,unstable,squeeze,whezzy,testing}?
You are correct about arch. To see available distros, check 
/usr/lib/xen-tools/.
> While the host sees /dev/mapper stuff and the md (RAID1), will the
> domUs see LVM disks as xvds by default?
The domUs will see the attached block devices just as you specify trhem 
in the config file. /dev/xvda[1,2,3...] is the most common case.
> Regardless of whether i create
> them directly with LVM or using xen-create-image?
Same thing. You could even mix different storage backends, you domU will 
not know the difference.

> Eh, the hardware's an Asus M2NPV-VM motherboard with an Ahlon64, 8GiB
> DDR2 RAM
I have used the very same MB and setup at home for some years. Worked 
like charm. The chipset temperature worried me a bit, so I glued a 
second cooler to the CPU's one, exactly above the chipset.
> There's an onboard
> nvidia Geforce and a PCI ATI/Asus Radeon HD 50** (i'd like to
> passthrough it to the desktop PV eventually).
Don't count on it. This MB does not supports IOMMU, required for the 
passthrough.

Greetings.

-- 
Alexandre Kouznetsov


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On Mon, 2013-01-21 at 20:40 +0000, Nuno Magalhães wrote:
> Greetings,
> 
> I'm fiddling with Xen at home, the dom0 is a freshly installed Debian
> stable (current 6.0.6 squeeze) using LVM over RAID.
> 
> I want to use two VGs, so the pointy-clicky won't really do since
> --lvm only takes one argument (i assume). That's no big deal, i can
> use LVM tools and even the partitions.d scripts xen-tools can use and
> provide a partition template through the  --partitions flag.
> 
> However, the man page refers:
> 
>          size       = 2Gb      # Disk image size.
>          image      = full     # Allocate the full disk size immediately.
>          memory     = 128Mb    # Memory size
>          swap       = 128Mb    # Swap size
> 
> These units are plain wrong, as they should be GB and MB. Regardless,
> are these 128 for --swap MB or MiB? And what about --size?
[...]
> PS: sorry if this is the wrong list...
Best place to report bugs against xen-tools (including docs bugs like
the above appears to be) is, according to [0], the Debian BTS.

I find reportbug(1) a useful tool for doing this, or you can find more
info on reporting a bug at http://www.debian.org/Bugs/

xen-tools also has its own user and dev lists, see [1].

Ian.

[0] http://xen-tools.org/software/xen-tools/bugs.html
[1] http://xen-tools.org/software/xen-tools/lists.html



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