Re: [Xen-devel] questions about production use

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

A couple of comments...

> The following technologies/architectures are on my research list and my
> stupid thoughts about the differences.
> 
> xen -> pros:
>    - near to "mainframe" architecture
>    - very high speed
>    - high scalability with very good resource isolation
>    - high stability (because relative low vmm complexity?)
>    - application compatibility very high
>    - open source
> xen -> cons:
>    - ? production quality, even with limited features (megaraid
> arrays)

I think we're pretty stable -- no one has complained about
problems for a long time (other than developers doing whacky
things with OSes other than the stock Linux). The supported
hardware list is growing steadily.

>    - ? practical experience with midrangeserver (4-8CPUs,
> 8-16GB RAM)

The biggest machine we've run it on is a 4CPU (actually 2x
hyperthreaded Xeon). We should scale with number of CPUs very
nicely. However, we only have support for 4GB physical ram. We
probably wont fix this until the x86_64 port, as PAE36 is such a
hack on current x86.

>    - ? always "on" developer community (security fixes)

We track the main 2.4 kernel pretty closely.

>    - relative high amount of codelines to patch linux kernels

Most of it is in arch/xeno, so it tends not to interfere with
other patches.

>    - ? less resource sharing/saver features like sparse files (uml)

CoW block devices are under development.

> virtuosso -> pros:  (datasheet statements, not verified)
>    - very high speed
>    - high stability
>    - manageability through webapplications (complexity/quality ?)
>    - SMP for virtual servers (i can't remember ... up to 16
>    CPUs)

We'll get around to this at some point...

>    - up to 64 GB RAM
> virtuosso ->  cons:
>    - not open source (I don´t know whats going on :-)
>    - customized linux kernels (very complex ???)
>    - fault tolerance between virtual servers (shared host OS)
>    - security between virtual servers (shared host OS)
> 
> user-mode-linux -> pros:
>    - open source
>    - production quality
>    - a relative large user community
>    - a "official" linux architecture
>    - good manageability (cow-files, sparse-files, flexible device-model)
>    - security between virtual servers (but shared host OS)
>    - fault tolerance between virtual machines (but shared host OS)
> user-mode-linux -> cons:
>    - a very high context switching rate
>    - relative low performance block devices (no "raw" access)
>    - resource consumption up to 80 percent and more (average ...40 ?)
>    - no SMP for virtual servers
>    - performance bottlenecks with high RAM servers
>    - small host OS patching required (only skas)
> 
> vmware -> pros:
>    - very stable system
>    - high quality software for datacenter users
>    - SMP (for ESX Server)
>    - installation of different native OS
>    - security between virtual machines (but shared host OS)
>    - fault tolerance between virtual servers (but shared host OS)
> vmware -> cons:
>    - resource consumption up to 50 percent and more? (average ...30 ?)
>    - special drivers for high performance required ?

Networking really sucks without the vxnet driver.

>    - very high price (GSX and ESX Server???)
>    - closed source
> 
> vserver -> pros:
>    - production quality
>    - a relative large user community
>    - very high performance
>    - good manageability, many tools for production use
> vserver -> cons:
>    - open source
>    - fault tolerance between virtual servers (shared host OS)
>    - security between virtual servers (shared host OS)
>    - relative high amount of codelines to patch linux kernels


Ian


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