Parallels Desktop .vs Disk Space shrinking.

Fernando N. wrote:

I thought I had done that in this sentence: "My disk (2TB) space reduced considerably after I switched from VMWare Fusion to Parallels and I can't really understand the reasons.". And the disk space continues to shrink, even though I have followed all the guidelines described above. Do you have any idea what might be causing it? I have taken it to Parallels support but nothing really helpful came up.

I agree with Etresoft -- the AI things you may find are hit or miss, I have found that for technical subjects (not just about Macs but other engineering in general), AI can be 50% WRONG. It can have consequences, so doing your own research is important.

I used to use Parallels and had back then ongoing disk space issues and Time Machine problems attributed to the very large single files that virtual machines utilize to represent an entire Windows system. Just logging in to the Windows system without doing anything makes that huge file look modified and then new snapshots are created.

There are snapshots created by the virtual machines, and then there are Time Machine snapshots. Both can take up massive amounts of disk space. Keep in mind also that use of Windows memory and its paging to disk all take up real Mac disk space. And apparently the size constraints specified in the Parallels setup can indeed be far exceeded when Parallels is running. See this post, it is probably outdated as it is from 8 years ago, but it will give you some insights about the challenge of managing disk space with large virtual machine allocations:

https://www.reddit.com/r/MacOS/comments/15pxjwn/parralels_taking_up_sizeable_amounts_of_system/

One solution suggested frequently is: move the entire virtual machine and its use of scratch or temporary space to an external fast SSD. Possibly, moving the VM to a separate VOLUME would also accomplish this as well. The idea is to prevent any use of temporary space on your main SSD by the virtual machine. Make sure that the VM volume is excluded from Time Machine backups so no snapshots of it are created for Time Machine. Apparently, when everything is on the primary SSD, even if you exclude the virtual machine folders from Time Machine, although that helps the TM backups to run quickly, I have read in some places that Time Machine snapshots can still be created for that content even though the files/folders are not being backed up in Time Machine. If this is still the case (I don't know if it is under Tahoe), then moving the entire virtual machine to an external drive or separate volume could resolve it.

Also, deleting snapshots and temporary files as you indicate you do may seem like it should be helpful, note that with APFS SSDs there can be a delay for the actual disk space to be freed up physically. Etresoft and others have explained why this is so better than I can in their other posts elsewhere. So even if you tell Parallels to remove hundreds of GB of snapshots or short term files, the space may show as "not available" or "not free" for some time afterwards (1 or 2 days).

If you do move your virtual machines to a separate volume, you will need to backup them up to yet another drive. You can do that with CCC or SuperDuper.

If I am correct or incorrect about what I say here regarding separate volumes for VMs, I hope others more expert than me will chime in to confirm or correct what I have suggested.

Note added: see Viking's separate post, apparently they have utilized an external drive for the VMs and it works well. Viking posted while I was typing ...

Fernando N. wrote:

If you don't mind my asking one more question... now I see something like "576.07GB free (465.65GB purgeable)"

Are you seeing something "like" that quoted string, or exactly that text? I don't see anywhere in the operating system where it would show this. In particular, the string "free" is virtually never used due to its unreasonable accuracy.

what is mac OS trying to tell me?

What are you trying to tell us? If you see something on the screen, please use a screenshot. Probably the worst thing you can do is paraphrase incorrectly using quotes. That's just wrong on all levels.

My interpretation is that out of the 576.07 free GB, 465.65 are free but do contain data that will be overwritten as needed. Is this what mac OS mean?

Here's what I'm talking about. This is a screenshot of my "Macintosh HD" from the Finder:

Is this what you're talking about? No where on this screenshot does it say "free". That's the point. There is, in fact, no information on this screenshot of any kind. With the exception of the "Format: APFS" line, every single piece of information here is wrong or misleading in some way.

If I go to Disk Utility > View > Show all volumes and click on the top-level APFS container volume on the startup drive, you can actually see the "free" storage on the volume:

I have 195.7 GB free on my 1 TB hard drive.

Your values may differ.

Use this application to see where space is being used 

Storeograph  Directly from the Developer 

Fernando N. wrote:

As the saying goes: "a picture paints a thousand words"... hope you can now see clearly what my question was about. The numbers have changed since my original post.

Yes. It's a very common problem. You're running out of free storage.

I would have preferred to see the output from Disk Utility. Some people like to use some formula to try to explain free vs. available storage, but I don't like that. A formula like that implies some kind of mathematical equation. When it comes to Apple's "available" storage, we're not talking mathematics. It's another section of the library - the fiction section.

According to that screenshot, you may have about 85 GB of free storage. That's not too bad. You just starting to get to the point where you'll have performance problems as the operating system struggles to keep enough free storage available to run. Normally that happens at about 60 GB. The operating system has several hidden system volumes that may consume up to 50 GB. Plus you may need another 50 GB or so for swap. And then you'll need some for highly volatile cache files.

So you're right on that edge. It says you have 432 GB of "purgeable" storage. But that's a bit misleading. Yes, you do have 432 of purgeable storage, but the operating system will make to do some work to make that available. And ironically enough, it will categorically refuse to touch any of that until you run completely out of storage.

My advice to you has not changed in the slightest. You're a heavy VM user. It was good that you spent extra money on that 2 TB drive. That bought you some time and some breathing room. But you can't neglect it forever.

Fernando N. wrote:

I have reduced the purgeable space by coaxing macOS to fill that space creating medium to large files and then removing them.

That's not an effective long-term strategy. The operating system can fill up that storage again. That's how you got into this spot in the first place. Any attempts to reduce "purgeable" or "cached" data are just temporary fixes. Usually people only discover this problem when they're trying to install an update. Nothing freaks people out like being denied round windows and overlapping transparent text.

So, no. I was not actually running out of disk space.

Quite obviously you were. Also, that's the wrong screenshot. You want to click on the "Container disk1" to see the actual free storage on the drive. In this screenshot, you've actually clicked on the read-only startup snapshot.

An APFS volume can contain multiple shared volumes, in addition to snapshots. There's no guarantee that a "free" amount on any volume is correct because individual volumes can have their own quotas. Plus, in your screenshot, it says "free" in one place and "available" in another. I don't trust any display that says "available".

If you click on "Container disk1", the free storage might actually be the same, but that's just because you get lucky. APFS is an exceptionally subtle disk format with an endless capacity for confusion, if not data.

Fernando N. wrote:

Now: of course, as a long-term strategy, if I want to continue doing what I am doing, exactly how I am doing it

But what is that?

All I can do is triple-down on my original recommendation. You really need to get a handle on your storage. I'm a fairly heavy user of VMs myself. I don't use them as much as I used to. Currently, I only have 3 macOS VMs on my 1 TB SSD. In the past, I've had many more, on smaller drives.

Unfortunately, large external SSDs are way too expensive here; even so I have moved my least important VM to an external HDD and that was what pointed me to the fact that Parallels does use a lot of space beyond that of the VM itself.

What is "large"? What is "expensive"? These are strictly relative terms. You already have a 2 TB SSD which is more than I can afford. You're talking about getting a new Mac with a 4 TB SSD. That would be insanely expensive.

Last year I spent $500 (Canadian) for a high-speed Thunderbolt 4 4 TB SSD. Is that large or expensive? I don't even use that for VMs as I have a stable 200 GB free on my internal drive. And I'm also a developer, which costs 300 GB in storage.

But you're talking about VMs of size 70GB and 58GB with double the size of my SSD, and half the free storage. That math just doesn't add up. I think you've got some forgotten files somewhere. For example, my VM system (the free Virtual Buddy) saves installer packages, which I totally don't need. But I had to use my Storage tool to notice that big usage and delete it.

I use Parallels Desktop Pro 26.2.2 on my M4 Mac Mini Pro 14c/20g/64 GB/1 TB configuration. My Parallel's guests all reside on my 2 TB TB5 OWC Envoy Ultra drive connected to the TB5 port on the mini. I never put VM guests on the Mac boot drive…

Right now, I have five guests configured: Windows 11 Pro, Ubuntu 25.04, macOS Monterey, Sonoma, and Sequoia.

There is a ~/Library/Application Support/Parallels Desktop folder consuming ~ 500 KB, a /Library/Parallels folder consuming 139 KB, and a ~/Library/Caches/com.parallels.desktop/console folder consuming 8.1 MB. That is it.

AI did not write this…

Fernando N. wrote:

AI Summary: (COMMENTS IN ALL UPPERCASE)

You need to describe your problem in your own words.