Why are the "offline" virtual disk operations resource hogs?

[JohnW3]

I have two defined VMs in Workstation Pro 12.5 on Win 7 (64) with 2.8GHz i7 processor with 32GB RAM. Almost never do I have both open at the same time. Every time I do something that manages the virtual disks (which has to be done when the VM is stopped)--like delete a snapshot, compact a disk, or other less frequent operations--everything else on my host computer slows significantly. Sometimes, it slows to a crawl where it has taken 30+ seconds to get the context menu on the Taskbar and several minutes to start Task Manager. These are off-line operations that always take significant time and it is very annoying to lose usage of my machine while they plod along. Their CPU usage is low, indicating they are largely I/O bound. So, why must they consume so much of the machine's resources?

My desired performance is to be able to run one VM while cleaning up the disk on the other, but Workstation won't allow that. Why not? The two VMs are distinct file sets and working on one shouldn't have any effect on the other.

Adding to this frustration, today's defragmentation operation failed after two hours, reporting that there is not enough available space. Did it really require two hours to deduce that?  I have 58GB free. How much space does it need? (And why isn't that requirement published somewhere that I could find?)

[wila]

Hi,

There can be many reasons for why your disk operations are so slow, but ..

Your complaint about needing a lot of space free for merging a disk is giving a hint.

If you use a single disk instead of separate disk slices for your virtual disk and you do any operations on them then a LOT of data has to be processed at the same time instead of working with just the slices.

It is almost always a better idea to have the hard disk stored in multiple files.

For VMware Workstation afaik there is no user interface to change this as in VMware Fusion, but you can still change it using the vmware-vdiskmanager command.

For a general idea on disk types look here:

http://sanbarrow.com/vmdk/disktypes.html

For the record, slices can be bigger as 2GB nowadays, but you're using monolithic sparse and as a result when you commit a snapshot, you need free space for at least your total disk size (eg. if your current disk size is 70GB and you try to commit a 3GB snapshot then you will need at least 70GB free while the two files are getting merged.

If you are using slices then you only need a bit more free space as the max slice sizes in order to merge the snapshots, if slices are max 4GB then having 5GB free might already be enough. Although I would suggest to make sure you have plenty of free space (eg. 10GB, so you do not run out of disk space while merging)

--

Wil

[JohnW3]

Thanks. That gives me something to work towards that has the hope of helping (after I buy more storage space so I have enough room to convert the file :smileygrin:).

Next, we need to convince VMware to not lock all the VMs when it is modifying only one of them.

[wila]

Hi,

I think the problem is windows... there's a couple of reasons why I think that:

- this just works as you are asking for on VMware Fusion, I use it all the time there.

- The GUI is throwing up a so called "modal dialog" to display the progress and as a result.. no other parts of the VMware Workstation GUI can be displayed.

That's standard windows behavior.

- While doing one of these operations, I _can_ actually start a vm via VMware Player (which is included in VMware Workstation, so you should have that as well)

--

Wil