[Xen-devel] questions about production use

[Manfred.Herrmann@xxxxxxxxxx]

After a couple of months in exploring...testing...TryToUnderstand
the alternatives in the "world of virtualization"
I have to decide
how to build a production server.

I would like to use xen as the mainframe-quality partitioning
system for high stability and high performance virtual
servers.
And in addition to that it would be a dream to run
vserver or uml
for low performance virtual servers within a xen-domain.

1. Is xen in a current release stable for my production
server?
2. What do you think about such a system, the pros
and cons?
3. Which system is the better try to patch for xen
usage, vserver
   (lot of linux capabilities and security
context code) or uml (lot
   of ptrace and mmap ... like code)?

Sorry for that monster mail :-)

Manni


xxxxxxxxxxxxxxxxxxxxx

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)
   - ? practical experience with midrangeserver
(4-8CPUs, 8-16GB RAM)
   - ? always "on" developer community
(security fixes)
   - relative high amount of codelines to
patch linux kernels
   - ? less resource sharing/saver features
like sparse files (uml)

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)
   - 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 ?
   - 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

IBM mainframe Linux ... mainframe to expensive for
me :-)