Re: Admin Guide: Tuning 21.1.2 Disks and virtual servers

[Buchan Milne <bgmilne@staff.telkomsa.net>]

On Saturday, 9 January 2010 22:30:09 Gavin Henry wrote:
> ----- "Francis Swasey" <Frank.Swasey@uvm.edu> wrote:
> > Is the info in this section intended for only physical LDAP servers or
> >
> > for servers that are virtual (such as VMware) as well?
> 
> Physical servers are faster as you have more control over the disks that
>  aren't shared underneath.

This isn't necessarily always the case. E.g., with Xen or KVM, you can quite 
easily dedicate a block device on the physical server to a specific virtual 
machine, which could be a local or remote (say, a LUN on a SAN array which has 
a few hundred spindles behind it) device. You aren't limited to using file-
backed images.

With VMWare with storage virtualisation, AFAIK, you could have virtual HBA(s) 
(with it's own dedicated WWN) accessing LUNs on a SAN.

Note that Red Hat has published some benchmarks with MySQL, showing that KVM 
has better CPU scalability than MySQL, and it is actually more beneficial to 
run MySQL VMs on hosts with more than about 8 cores, instead of running on the 
"bare metal".

Regards,
Buchan