VMWare, virtual disks, ASE, RH Linux

[Database Administrator]

We're dipping our toes in virtual waters here. Anyone know
any references on how best to set up the virtual
disks--especially regarding performance? I am told the
standard method, or maybe that's most flexible method, when
running the VM host on a Linux system is to for the VM host
to use a conglomeration of a large set of files on its Linux
base and represent these as virtual disks to the various
virtual machines. From a DB perspective, of course, that
puts us a long way from the hardware. It makes me a little
nervous. If you have references, experiences, whatever, I'm
open to information. Thanks.

[Database Administrator]

John Richter wrote:
> We're dipping our toes in virtual waters here. Anyone know
> any references on how best to set up the virtual
> disks--especially regarding performance? I am told the
> standard method, or maybe that's most flexible method, when
> running the VM host on a Linux system is to for the VM host
> to use a conglomeration of a large set of files on its Linux
> base and represent these as virtual disks to the various
> virtual machines. From a DB perspective, of course, that
> puts us a long way from the hardware. It makes me a little
> nervous. If you have references, experiences, whatever, I'm
> open to information. Thanks.

Yes...

1. lock the virtual machine memory into physical RAM (on the host os,
you need to configure 'fit all memory into host ram' or similar)
2. lock the ASE memory into physical ram -- see my blog post on how to
do this (linux):
http://froebe.net/blog/2007/12/31/ha...ase-ase-linux/
3. use linux as the client os as ASE on Windows in a vm environment
seems to have performance problems.
4. use files (with dsync disabled and directio enabled) not raw
partitions for your database devices
5. make sure your virtual machine's clock and host clock are
synchronized - the method to do this varies depending on the vm
environment (vmware, etc)
6. disable antivirus scanning of the directory that the virtual machine
resides in
7. do NOT run any other application on the host machine except for
other vm's.

hope this helps

Jason L. Froebe
TeamSybase
ISUG Board Member
http://www.froebe.net/blog