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Re: [Xen-users] guests max limit

On Sat, Jul 9, 2011 at 9:36 PM, Luis Roberto Romano
<luisromano@xxxxxxxxx> wrote:
> Thanks Zary.
> I meant a number limit (e.g. 4 DomUs). Now I see (by your answer) that I was
> wrong.

There's always a limit.

For example, domU ID is always increasing, so (in the past anyway) you
can only have a certain number of domUs before having to reboot dom0
(IIRC in the past this limit was 65k or something, it might have been
changed in current versions).

Also, I did some simple test with a busybox-based initrd, using a
small amount of memory. On that test, after 300 domUs or so xenstored
consumed very high CPU load which makes it unusable. Again, this is
some time ago, so current version might behave differently.

In practice, it should be long before you hit those kinds of limit, so
you could usually ignore them. What you'll find is you're going to
stumble against some practilcal limits, like the one Zary mentioned
about memory. Also, if your domUs are busy (e.g. typical scenario if
you're a VPS hosting provider), your bottleneck will most likely be
disk IOPS.


> Regards!!!!
> 2011/7/9 Zary Matej <matej.zary@xxxxxxxxx>
>> >________________________________________
>> >From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
>> > [xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Luis Roberto Romano
>> > [luisromano@xxxxxxxxx]
>> >Sent: 08 July 2011 17:48
>> >To: xen-users@xxxxxxxxxxxxxxxxxxx
>> >Subject: [Xen-users] guests max limit
>> >
>> >Hi.
>> >
>> >I need to know how many DomUs can I get running on a Dom0. I'm using Xen
>> > 4.0 over Debian Squeeze.
>> >
>> >Thanks!!!!
>> >
>> >
>> >Luis
>> >
>> Hi, I guess the host RAM will be the first limit of concurrent running
>> DomUs. You can squeeze only so much RAM into single physical host (unless we
>> are taling about host with 128 GB RAM and 64 MB RAM DomUs :D).
>> Regards
>> Matej
> --
> ----------------------------------------------------------
> Luis R. Romano
> Estudiante de Ingeniería en Computación.
> Twitter: @luirro777
> Facebook: facebook.com/luirro
> Blog: www.luisrobertoromano.com.ar
> Linkedin: http://ar.linkedin.com/pub/romano-luis/9/265/848
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