Disable .vmem in VMware

If you run VMware Workstation or Fusion on mechanical HDDs or wear-sensitive SSDs, you may have noticed severe disk thrashing caused by background memory paging. VMware default settings often write guest memory pages to persistent .vmem files on the host disk, saturating storage I/O and causing system-wide lag.

---

The Solution: Force In-RAM Execution

To eliminate .vmem file generation and stop VMware from paging guest RAM to your host storage, add the following configuration block to your VM's .vmx file (or globally in settings.ini / preferences):

# Lock 100% of guest memory into physical host RAM
prefvmx.minVmMemPct = "100"

# Disable dynamic memory trimming back to host
MemTrimRate = "0"

# Prevent creation of the .vmem backing file on host disk
mainMem.useNamedFile = "FALSE"

# Disable redundant memory page sharing scans
sched.mem.pshare.enable = "FALSE"

# Automatically lock the recommended memory allocation size
prefvmx.useRecommendedLockedMemSize = "TRUE"

---

What Each Parameter Does

• mainMem.useNamedFile = "FALSE": Stops VMware from allocating a full .vmem disk file matching the guest's RAM capacity.
• prefvmx.minVmMemPct = "100": Demands that 100% of the virtual machine's provisioned RAM remains pinned in physical host memory rather than being paged out.
• MemTrimRate = "0": Prevents the hypervisor from constantly unmapping and trimming unused guest memory, avoiding bursty host disk I/O.
• sched.mem.pshare.enable = "FALSE": Disables transparent page sharing (TPS) scanning, eliminating unnecessary background CPU and disk comparisons.
• prefvmx.useRecommendedLockedMemSize = "TRUE": Directs VMware to reserve and lock host RAM according to optimal memory sizing guidelines.

---

Implementation Note

Make sure to shut down your virtual machine completely before editing its .vmx file. Because this configuration locks the guest's entire memory space into physical host RAM, ensure your host has enough free physical memory before launching multiple VMs simultaneously.