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Hi Andrew,

as allways it depends on your needs what is best for you.

If you are planning to run multiple VMMs (maybe 3 or 7 :-) on that
machine I would suggest to take the 4x box, because you have more cpu
power and each machine has its own cpu, on the other hand if your VMMs
are going to be idle most of the time that it might be better to take
the 2x one, because you have more peak cpu power. But anyhow 256MB is a
bit less to run many VMMs on that machine with dom0 and 3 domU every
gets 64MB, with 7 domU there will be only 32MB for each machine. And
don't forget to think about energy consumtion, a 4 cpu machine like that
can use *quite a bit* of electrical power, so if running 24/7 that will
cost a lot, so it might be cheaper to by a newer machine. As said
before, it depends on the use.

Regards,
Mario Minati

Andrew Thompson schrieb:

> I'm looking over a couple of used systems that I can get for less than
> 150USD. I can't seem to decide if I should splurge and get a 4x box
> for 25 dollars more than a 2x at a slightly higher clockspeed.
>
> 112952-001-B1-06 Proliant 6500 - 4xPIII Xeon500MHz/1MB, 256MB
> 100738-003-B1-06 Proliant 5500 - 2xPIIIXeon550MHz/512KB, 256MB
>
> Any suggestions?
>
> I read that domU's will be able to see multiple processors in a later
> version of Xen. Should I go for the 4x hoping that feature will be
> supported with 32bit chips? It seems a lot of development talk I've
> been reading recently is in the 64bit arena.
>
>_______________________________________________
>Xen-users mailing list
>Xen-users@lists.xensource.com
>http://lists.xensource.com/xen-users
>


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> I'm looking over a couple of used systems that I can get for less than
> 150USD. I can't seem to decide if I should splurge and get a 4x box for
> 25 dollars more than a 2x at a slightly higher clockspeed.
>
> 112952-001-B1-06 Proliant 6500 - 4xPIII Xeon500MHz/1MB, 256MB
> 100738-003-B1-06 Proliant 5500 - 2xPIIIXeon550MHz/512KB, 256MB
>
> Any suggestions?

Well... As other people have said, it partly depends on how many domUs you're
going to run!

That said, $25 for 2 more CPUs looks pretty good to me, especially given
you're getting double the cache (which will tend to negate the MHz
difference).

Either machine will probably want a RAM upgrade if you want to have decent
memory sizes in your virtual machines but RAM is cheap, after all.

> I read that domU's will be able to see multiple processors in a later
> version of Xen. Should I go for the 4x hoping that feature will be
> supported with 32bit chips? It seems a lot of development talk I've been
> reading recently is in the 64bit arena.

Unstable will do SMP on x86 already and it's in the process of being
optimised. 3.0-stable will sport the optimised implementation.

In the meantime, if you have 3 or more domUs, you'll still be able to put
those CPUs to some good use.

Cheers,
Mark

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> IMO, the limiting factor is not CPU but RAM available to a virtual
> machine. it would be nice if there were some way to let memory float
> between virtual machines based on need. In the other hand, it may be
> there already and I just haven't figured it out.

It doesn't happen automatically - you'd have to use the balloon driver to
shrink one domain and grow another one. A feature we'd like to see is
"auto-ballooning" where dom0 will adjust domU memory footprints based on
their current utilisation. This is likely to appear at some stage in the
future...

Cheers,
Mark

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Andrew Thompson wrote:
> I'm looking over a couple of used systems that I can get for less than
> 150USD. I can't seem to decide if I should splurge and get a 4x box for
> 25 dollars more than a 2x at a slightly higher clockspeed.
>
> 112952-001-B1-06 Proliant 6500 - 4xPIII Xeon500MHz/1MB, 256MB
> 100738-003-B1-06 Proliant 5500 - 2xPIIIXeon550MHz/512KB, 256MB
>
> Any suggestions?
>
> I read that domU's will be able to see multiple processors in a later
> version of Xen. Should I go for the 4x hoping that feature will be
> supported with 32bit chips? It seems a lot of development talk I've been
> reading recently is in the 64bit arena.

personally, I would go for the most memory. Usually, you can remove
CPUs if consumption power is an issue. The difference in CPU speed is
negligible.

IMO, the limiting factor is not CPU but RAM available to a virtual
machine. it would be nice if there were some way to let memory float
between virtual machines based on need. In the other hand, it may be
there already and I just haven't figured it out. I'm still running
2.0.5 because of some of the noises I've seen about lvm and I'm looking
for a quiet moment when I can risk killing my xen machine.

---eric

--
http://www.wired.com/wired/archive/13.03/view.html?pg=5

The result of the duopoly that currently defines "competition" is that
prices and service suck. We're the world's leader in Internet
technology - except that we're not.

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Mark Williamson wrote:
>>112952-001-B1-06 Proliant 6500 - 4xPIII Xeon500MHz/1MB, 256MB
>>100738-003-B1-06 Proliant 5500 - 2xPIIIXeon550MHz/512KB, 256MB
>>
>>Any suggestions?
>
> Well... As other people have said, it partly depends on how many domUs you're
> going to run!

I'm still so new at setting it up, I don't know how many I'll be running.

> That said, $25 for 2 more CPUs looks pretty good to me, especially given
> you're getting double the cache (which will tend to negate the MHz
> difference).

I thought it might be good to post the specs. Thx

> Either machine will probably want a RAM upgrade if you want to have decent
> memory sizes in your virtual machines but RAM is cheap, after all.

That's one of the reasons I'm planning on picking up a new machine.
Currently I'm running on a Dual P2 300 Dell "Workstation" that won't
accept any RAM that I've been able to find. It has 128 currently, so
this will be a 100% increase. :)

>>I read that domU's will be able to see multiple processors in a later
>>version of Xen. Should I go for the 4x hoping that feature will be
>>supported with 32bit chips? It seems a lot of development talk I've been
>>reading recently is in the 64bit arena.
>
> Unstable will do SMP on x86 already and it's in the process of being
> optimised. 3.0-stable will sport the optimised implementation.

I'll be looking forward to that.

> In the meantime, if you have 3 or more domUs, you'll still be able to put
> those CPUs to some good use.

I'm sure I'll come up with something to spin cycles on. Perhaps I'll let
distributed.net and SETI@HOME duke it out on a spare cpu.

--
Andrew Thompson
http://aktzero.com/