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Storage on Slicer for Mac

Slicer for Mac stores VM state using a base image flow with copy-on-write clones.

You can set storage size per host group with storage_size in slicer-mac.yaml.

Use nG style values (for example 15G), and set at least 5G to give enough initial headroom.

Sparse files are used, so disk space is not allocated up front. A declared size of 15G represents logical size and grows as data is written.

Image/bootstrap workflow

Each host group (slicer, sbox) follows the same process:

First start

  1. Pull the image from config.image and unpack it into the local OCI cache.
  2. Build the host-group base image (for example ./slicer-base.img).
  3. Extract the kernel to ./kernel/<host_group>/Image.
  4. Create the first VM disk from that base image.

New VM start (warm path)

  1. Reuse the OCI cache.
  2. Reuse the host-group base image.
  3. Clone the VM disk with APFS copy-on-write:
cp -c ./slicer-base.img ./slicer-1.img
  1. Start the VM from the clone.

If cp -c is unavailable, the tool falls back to a normal file copy.

Why storage sizes look smaller than expected

slicer-base.img, slicer-base, and VM .img files are sparse. A size like 15G is a logical size and grows as data is written. Use the nG format and keep the value at least 5G.

Rebuild or reset local state

To force a full rebuild from OCI:

rm -f ./slicer-base.img
rm -rf ./kernel/slicer ./kernel/sbox
rm -rf ./oci-cache

To remove a single VM image and recreate it from the host-group base image:

rm -f ./slicer-1.img

Troubleshooting

If your VM crashes for some reason, or the Mac's sleep mode causes an issue with the VM, you may find the .img file needs to be checked or repaired with the e2fsck utility.

e2fsck -f ./slicer-1.img

You can obtain e2fsck by installing the e2fsprogs package via brew install e2fsprogs. Brew is available separately at: https://brew.sh/.