Parallel Windows VM taking more and more space

VikingOSX wrote:

On that guest Windows 11 Pro Configuration panel in the General pane, there is a check box to Reclaim disk space on shutdown.

That's the one I was thinking of!

I am running Parallels Desktop Pro 20.2.1 on a 2020 27-in Core i7 iMac with Sequoia 15.3.1. The Windows 11 Pro 24H2 guest is installed on an external 1 TB USB-C 3.2 Gen 2 SSD connected to a TB3 port. On that guest Windows 11 Pro Configuration panel in the General pane, there is a check box to Reclaim disk space on shutdown. I have that checked.

I would never install a Virtual Machine guest on the startup drive, especially if it was only a 256 GB unit. Regardless of the vendor, operating systems grow in size over time and Windows 11 is no exception. I hope you have Time Machine configured to exclude that Virtual Machine guest folder, because each time you use that guest, it will have changed and that will trigger Time Machine to back it up.

Are you checking to see that the Windows VM doesn't need to be reduced in size within the Parallels app itself? Typically, after doing any Windows updates, it is a good idea to check.

AFAIK, running Parallels on a M-series Mac is still a "work in progress." FWIW, I have been using Parallels for years with my Intel Macs, but have only had limited success with its implementation on my silicon ones. In addition, using VM managers on a Mac (regardless of CPU) with limited internal storage space (< 1TB) is a recipe for "trouble."

A few days of simple browsing is also a few days of Windows running background updates and generating all kinds of temporary files. There are a number of things Windows can do to recover space itself - but only if running for long enough. Parallels does have a built-in feature to recover disk space from the VM - by which it will use Windows own internal clean up mechanisms and then also compress some things in the disk image for efficiency.

Can't recall off the top of my head, but I think both Windows itself and Parallels have options for those clean-up activities to be run on schedule - in particular on shut down.

I haven't run Parallels for a very long time, but I have a vague recollection that there was an option in settings to recover disc space.

To get to this option, simply right-click on the Parallels VM "directory" entry for your Windows VM. It should show up as one of the options.

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