VHD placement - on faster/same OR slower/different disk ?

Hello,

I am not sure, if to store VM files

on faster, but the same physical disk as the system,
( on data partition - system one does not have enough space),

SATA II AHCI 7200RPM, 250GB, 50GB system+200GB data,
typical max steady transfer speed 60-80 MB/s)

or on slower, but separate PATA IDE disk 5400RPM,
ATA mode not handy, transfers about 30 MB/s.

Speed speaks for the former, but there can be "fight" over disk
operation between host and guests.
The fight cound be mitigated by NCQ AHCI feature.

What is major opinion ?

--
Poutnik
The best depends on how the best is defined.

On Wed, 21 Oct 2009 17:35:24 +0200, Poutnik <> wrote:

>Hello,
>
>I am not sure, if to store VM files
>
>on faster, but the same physical disk as the system,
>( on data partition - system one does not have enough space),
>
>SATA II AHCI 7200RPM, 250GB, 50GB system+200GB data,
>typical max steady transfer speed 60-80 MB/s)
>
>or on slower, but separate PATA IDE disk 5400RPM,
>ATA mode not handy, transfers about 30 MB/s.
>
>Speed speaks for the former, but there can be "fight" over disk
>operation between host and guests.
>The fight cound be mitigated by NCQ AHCI feature.
>
>What is major opinion ?

A separate disk. Windows is a pretty disk heavy OS, so when you have
2 Windows OSes using the same disk you see a perf hit.
IMHO, you will probably still see better overall performance, host and
guest, if you move the VM to the 2nd disk.

--
Cheers,
Steve Jain, Virtual Machine MVP
http://vpc.essjae.com/
http://smudj.wordpress.com/

In article <>, noreply.-
@-.essjae.com says...
>
> On Wed, 21 Oct 2009 17:35:24 +0200, Poutnik <> wrote:
>
> >Hello,
> >
> >I am not sure, if to store VM files
> >
> >on faster, but the same physical disk as the system,
> >( on data partition - system one does not have enough space),
> >
> >SATA II AHCI 7200RPM, 250GB, 50GB system+200GB data,
> >typical max steady transfer speed 60-80 MB/s)
> >
> >or on slower, but separate PATA IDE disk 5400RPM,
> >ATA mode not handy, transfers about 30 MB/s.
> >
> >Speed speaks for the former, but there can be "fight" over disk
> >operation between host and guests.
> >The fight cound be mitigated by NCQ AHCI feature.
> >
> >What is major opinion ?
>
> A separate disk. Windows is a pretty disk heavy OS, so when you have
> 2 Windows OSes using the same disk you see a perf hit.
> IMHO, you will probably still see better overall performance, host and
> guest, if you move the VM to the 2nd disk.

Then I will keep the current state.
I already have them on the separate disk,
thinking similarly.
I was not sure, if my idea was right.

thank you for the response.

--
Poutnik
The best depends on how the best is defined.