// VMware Migration IN BETA

[ ZeroCow ]

Cut your migration window
from weeks to minutes.

Traditional VMware migrations eat entire maintenance windows — days of planning, hours per VM, weekends lost. zcow eliminates all of that. Atomic metadata transformation converts VMDK to QCOW2 in from seconds to minutes and not hours, with zero data movement and instant rollback. Your team gets their weekends back.

Get Early Access How it works
s-mins not hours, per VM
~0 hours maintenance window
100% integrity guaranteed
// HOW IT WORKS

Seconds to minutes per VM. Not hours.

zcow rewrites only the metadata — VMDK headers and extent maps transform to QCOW2 in-place. No data copies, no waiting, no surprise overruns. Your maintenance window is measured in minutes, not weekends.

zcow · migration engine 
$ zcow convert vm-prod.vmdk

  Parsing VMDK metadata ............ ✓
  Validating disk geometry .......... ✓
  Validating extent table ........... ✓
  Rewriting QCOW2 header ............ ✓
  Remapping extent pointers ......... ✓
  Committing atomic write ........... ✓
  Verifying integrity checksum ...... ✓

  ✓ Migration complete in 4.2s  (traditional: ~3 hours)
  ✓ Data moved: 0 bytes · Integrity: verified
  ✓ Output: vm-prod.qcow2 — ready for QEMU/KVM

$ █
01

Parse & validate

zcow reads VMDK metadata headers and validates disk geometry, extent maps, and snapshot chains — typically completing in under 10s regardless of disk size.

02

Atomic transform

Metadata rewrites to QCOW2 in a single atomic transaction — no partial state, no window for failure. If anything goes wrong, your VM is completely untouched and back online instantly.

03

Verify & boot

Integrity checksums confirm conversion in milliseconds. The resulting QCOW2 is immediately bootable on QEMU/KVM — no post-processing, no waiting, no extended outage.

// THE DIFFERENCE

Others block your weekend.
ZeroCow takes minutes.

Traditional migration
Weekend maintenance windows — days of scheduling
Hours of downtime per VM, more for large disks
100 GB disk = 100 GB copied — time scales linearly
Failure mid-copy = extended outage, manual recovery
No rollback — once started, you're committed
[ ZeroCow ]
Entire fleet migrated in a single planned window
Seconds to minutes per VM — disk size is irrelevant
Metadata rewrite only — <1 MB written per conversion
Atomic commit — failure = zero impact, VM back instantly
Instant rollback at any point — no risk, no extended outage
// CAPABILITIES

Your maintenance window just got a lot shorter

Flat conversion time

Only metadata is rewritten. A 10 TB disk takes the same seconds-to-minutes as a 10 GB one — conversion time is decoupled from disk size entirely.

Safe to run in-hours

Every conversion is a transactional write. If anything fails, the original VMDK is untouched and the VM is back online in seconds — no extended outage, no incident.

Instant rollback

Change of plans? Roll back to the original VMDK with a single command. Your outage window is bounded — you're never stuck mid-migration with no exit.

Customised fleet migration

Migrate entire VMware clusters in parallel. What used to take weeks of staggered maintenance windows now fits in a single planned slot. Every deployment is unique, wrap the tool with automation suited to your environment.

Minimal downtime window

Schedule migrations during business hours without the risk of blowing out your change window.

Integrity verified

Post-conversion checksums validate every migration against the original. QCOW2 output is immediately bootable on QEMU/KVM.

// EARLY ACCESS · IN BETA

Stop losing weekends to migrations.

ZeroCow is in beta. Join the waitlist and be among the first teams to run fleet migrations in a single planned window — not across weeks of painful maintenance slots.

No spam. Early access updates only.