Vista - Performance fixed disk vs dynamic?

03-13-2009

How much faster is a fixed vhd disk compared to a dynamically growing?

03-13-2009

On Fri, 13 Mar 2009 12:43:29 +0100, Magnusb <magnusb@xxxxxx> wrote:

Quote:

>How much faster is a fixed vhd disk compared to a dynamically growing?

Depends on what disk operations you are doing. If you save large
chunks of data to the dynamic disk then it will expand itself for each
N Mb of new data (where N is a number like 5-10, I don't remember
now).

However the most common source of slow accesses is that the VHD file
resides in MyDocuments on the C: drive. A sure showstopper since then
both the host and the guest need to access the same drive all the
time.
Move the VHD to a different spindle (different physical drive).

--

Bo Berglund (Sweden)

03-13-2009

On Fri, 13 Mar 2009 17:29:56 +0100, Bo Berglund <boberglund@xxxxxx>
wrote:

Quote:

>On Fri, 13 Mar 2009 12:43:29 +0100, Magnusb <magnusb@xxxxxx> wrote:
>

Quote:

>>How much faster is a fixed vhd disk compared to a dynamically growing?

>
>Depends on what disk operations you are doing. If you save large
>chunks of data to the dynamic disk then it will expand itself for each
>N Mb of new data (where N is a number like 5-10, I don't remember
>now).
>
>However the most common source of slow accesses is that the VHD file
>resides in MyDocuments on the C: drive. A sure showstopper since then
>both the host and the guest need to access the same drive all the
>time.
>Move the VHD to a different spindle (different physical drive).

Dyn-disks expand in 2MB chunks.

If you're reading from one, there's no real difference. Generally, on
most fast systems you won't notice much of a difference.

Running a VHD on our C: drive, as Bo says, will make a perf hit.

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

03-13-2009

In article <bb2lr4p8vqvts2mjm4rnjrbtntj9c5upuu@xxxxxx>,
boberglund@xxxxxx says...

Quote:

> Depends on what disk operations you are doing. If you save large
> chunks of data to the dynamic disk then it will expand itself for each
> N Mb of new data (where N is a number like 5-10, I don't remember
> now).

It does include frequent writes of data. However not sure if it is that
much writing new data, rather deleting files/creating new file. Not sure
if that require the dynamic disc to expand in size (until compacted) or
if it will reuse space within the vhd disk.

03-13-2009	#1 (permalink)
Magnusb n/a posts	Performance fixed disk vs dynamic? How much faster is a fixed vhd disk compared to a dynamically growing?
My System Specs

03-13-2009	#2 (permalink)
Bo Berglund n/a posts	Re: Performance fixed disk vs dynamic? On Fri, 13 Mar 2009 12:43:29 +0100, Magnusb <magnusb@xxxxxx> wrote: Quote: >How much faster is a fixed vhd disk compared to a dynamically growing? Depends on what disk operations you are doing. If you save large chunks of data to the dynamic disk then it will expand itself for each N Mb of new data (where N is a number like 5-10, I don't remember now). However the most common source of slow accesses is that the VHD file resides in MyDocuments on the C: drive. A sure showstopper since then both the host and the guest need to access the same drive all the time. Move the VHD to a different spindle (different physical drive). -- Bo Berglund (Sweden)
My System Specs

03-13-2009	#3 (permalink)
Steve Jain [MVP] n/a posts	Re: Performance fixed disk vs dynamic? On Fri, 13 Mar 2009 17:29:56 +0100, Bo Berglund <boberglund@xxxxxx> wrote: Quote: >On Fri, 13 Mar 2009 12:43:29 +0100, Magnusb <magnusb@xxxxxx> wrote: > Quote: >>How much faster is a fixed vhd disk compared to a dynamically growing? > >Depends on what disk operations you are doing. If you save large >chunks of data to the dynamic disk then it will expand itself for each >N Mb of new data (where N is a number like 5-10, I don't remember >now). > >However the most common source of slow accesses is that the VHD file >resides in MyDocuments on the C: drive. A sure showstopper since then >both the host and the guest need to access the same drive all the >time. >Move the VHD to a different spindle (different physical drive). Dyn-disks expand in 2MB chunks. If you're reading from one, there's no real difference. Generally, on most fast systems you won't notice much of a difference. Running a VHD on our C: drive, as Bo says, will make a perf hit. -- Cheers, Steve Jain, Virtual Machine MVP http://vpc.essjae.com/
My System Specs

03-13-2009	#4 (permalink)
Magnusb n/a posts	Re: Performance fixed disk vs dynamic? In article <bb2lr4p8vqvts2mjm4rnjrbtntj9c5upuu@xxxxxx>, boberglund@xxxxxx says... Quote: > Depends on what disk operations you are doing. If you save large > chunks of data to the dynamic disk then it will expand itself for each > N Mb of new data (where N is a number like 5-10, I don't remember > now). It does include frequent writes of data. However not sure if it is that much writing new data, rather deleting files/creating new file. Not sure if that require the dynamic disc to expand in size (until compacted) or if it will reuse space within the vhd disk.
My System Specs

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