[CentOS-virt] Xen Database vms

compdoc compdoc at hotrodpc.com
Fri Jan 15 16:33:24 UTC 2010

-----Original Message-----
centos-virt-bounces at centos.org
[mailto:centos-virt-bounces at centos.org] On Behalf Of Ben M.
Sent: Friday, January 15, 2010 8:56 AM
To: Discussion about the virtualization on CentOS
Subject: Re: [CentOS-virt] Xen Database vms


What if it were the only "real" active vm? I know that might
sound a bit 
of a waste, but I am really enjoying the backup and
abilities of running in a Xen hypervisor as well as its
other features. 
It seems to be saving me a lot of time in production
settings. And there 
is also a comfort level in uniformity on a LAN.

Would there still be a significant hit on resource
performance by the 
hypervisor if running that database server alone in it, or
alongside a 
few rarely used, lightweight or spurious vms? I am talking
about the 
database activities running during the biz day and backups,
batches and 
other maintenance in the off hours. Nothing urgent here,
just trying to 
plan out the future, mull over the possibilities and where
to head.

- Ben
-----Original Message-----

I think it could work well. Having a server in a vm makes it
more portable. 

Many of my servers and services are running in vms on two
centos 5.4 servers: openfiler, efw firewall, trixbox 2.8,
SME Server (in server mode for email and spamassassin),
windows 2003 server, windows 2008 server, windows 7, and
others that aren't running.

I would suggest:

If there are a lot of temp files or disk access to the OS,
install the vm OS on a block device rather than to a file.
The storage should be on a local block device as well. 

If there's a lot of lan traffic to/from the other vms,
install a 3rd ethernet card in the server that is only used
for db traffic. 

I also use a virtual network that the vms can use to reach
each other. This is basically a private internal lan running
across the host machine's buses, rather than through your
network switch.

I get native performance with my set up...

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