[tech] mylah and musundo repurposing, virtualisation and storage

James Andrewartha trs80 at ucc.gu.uwa.edu.au
Wed Feb 10 20:53:29 WST 2010

On Tue, 9 Feb 2010, Nick Bannon wrote:

> On Tue, Feb 09, 2010 at 12:08:03PM +0800, James Andrewartha wrote:
> [...]
> > There's still some open questions:
> >  o If we make mylah a Xen server, what OS should be used for the dom0? 
> >    Debian, which may have problems with multiple CPU domUs, or CentOS 5.4 
> >    which will be harder to maintain? Or OpenSolaris, which has its own 
> >    well-integrated Xen support and fancy network management (Crossbow)?
> >  o What virtualisation software do we use for the Sun servers from Arts, 
> >    when they arrive? Do we want to virtualise Windows Server 2008, which
> >    will require using VMWare, or dedicate an entire machine to it? Or run 
> >    VMWare on one, and Xen on the others? Again, if Xen, what dom0 OS?
> We're in the happy position that we have more decent hardware than we
> know what to do with. It's nice to use a few platforms to let UCC members
> learn about them, some for "production" and there can be others out in
> the clubroom to experiment with and ponder upgrades with. I'm looking for
> to the next round of handmedowns with amd64 and VT support, to make kvm
> (and xenner, not so good at SMP either, yet) decent options.

The first such handmedown may arrive soon - troppo is being retired and 
donated to UCC. It's a Q6600 with VT and 8GB of RAM.

> I'd like to give Windows Server 2008 most of a machine, with VMWare,
> it'll let us share the console and snapshot it nicely. 

Yeah, [MRD] seems keen to run it under VMWare too.

> I'd like to
> have a couple of similar Xen machines, with working live migration.
> Easy to get slack and never upgrade those, though, hence we might need
> test machines in the clubroom that don't run all the time.

Live migration does require machines with CPUs from the same manufacturer 
(and ideally the same model) which may be a challenge with hetrogenous 
handmedowns. Although, now that I think about it, mermaid and mylah have 
similar enough CPUs that it should be feasible, but their differing 
versions of Xen could be a problem.

> Whoever reinstalls mylah can choose, but try to get them to promise to
> involve others in the regular maintenance.

CentOS seems to be the way to go, as OpenSolaris just integrated Xen 3.4 
so it's probably a bit early for production use. The only trick will be 
PCI passthrough of the SCSI controller for amanda.

> I think we need a gigabit switch in each rack for cabling sanity.
> I don't think we need a second just for SAN, yet, but it really might
> be worth:
>   * coloured SAN cables or cable tags;
>   * physically placing the storage ports at one end of the switch; and
>   * possibly not just throwing the traffic into the general VLAN trunk,
>     instead physically patching a few storage ports between each switch.
>     That would gain most of the real, tactile, "here's where the storage
>     traffic flows, it's a bit less likely to explode if someone mistypes
>     a config"


> That does sound good, thanks for the benchmarks.

Here's another, with a 36GB FC drive used as a separate intent log:

Version  1.96       ------Sequential Output------ --Sequential Input- --Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
musundo-b130    16G    40  98 71699  59 51738  41   101  99 190597  56  1666  62
Latency               569ms    5398ms    3647ms     152ms     190ms     188ms

which shows better performance despite the 36GB drive being slower than 
all the other drives.

musundo will also be getting a second CPU board with another 2 1.2GHz 
US-III+ SPARCs and 8GB of RAM.

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