Re: [Xen-users] Re: Differences in performance between file and LVM based images.

["Jeff Lane" <sundowner225@xxxxxxxxx>]

For what its worth, it should be fairly obvious also that using files
for the domUs becomes increasingly poor in performance as you add
domUs.

For an extreme case of this, I had 60 domUs going on a 4 node IBM x460
under SLES10/Xen.  All the DomUs used files for their filesystems and
all of those were stored on a multiple disk LVM volume that was spread
across three of the nodes.

All 60 of the DomUs were bootable and did in fact run, BUT the access
time was so slow that just logging in to one of them took a
considerable amount of time.

I have also observed that the type of disks you are using as storage
space can greatly effect the apparent performance.  Good example was
running 6 domUs using files instead of physical disks on a SATA RAID
array vs running the same things off a SCSI RAID array using 15K RPM
disks...

Personally, I kinda expected that result, and just for the grain of
salt factor, I did not use any real benchmarking to observe this, this
is all just my observations of the usability of the domUs in various
storage configurations...

Also, these were all paravirtualized domUs... no full virtualization was done...

On 8/23/06, Ligesh <myself@xxxxxxxxxx> wrote:
> On Wed, Aug 23, 2006 at 05:52:13PM +0200, Petersson, Mats wrote:
> >
> > Probably yes. How much? Don't know.
> >
> > But I was more referring to the fact that different applications do
> > different things to disks in the first place, so the application
> > behaviour may depend on "seek time" or "write time" or "read time" in
> > different proportions [1], so just using "hdparm" or something like that
> > wouldn't really be a useful measure of how some particular application
> > will perform on any given setup.
--
------------------> Jeffrey Lane - W4KDH <-------------------
                     www.jefflane.org
               Another cog in the great
                    Corporate Wheel

The internet has no government, no constitution, no laws, no
rights, no police, no courts.  Don't talk about fairness or
innocence, and don't talk about what should be done.  Instead,
talk about what is being done and what will be done by the
amorphous unreachable undefinable blob called "the internet
user base." -Paul Vixie

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users