Storage vMotion fails at 18% with the vmware.log error: Cannot allocate memory
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Storage vMotion fails at 18% with the vmware.log error: Cannot allocate memory


Article ID: 310470


Updated On:


VMware vCenter Server VMware vSphere ESXi


  • Storage vMotion (svmotion) fails at 18%.
  • The virtual machine's vmware.log file contains entries similar to:

    Worker#0| DISKLIB-VMFS :CopyData '/vmfs/volumes/{datastore}/{vm-name}/{vm-disk-file}-flat.vmdk' : failed to move data (Cannot allocate memory:0xc0009).
    Worker#0| DISKLIB-LIB : DiskLib_Clone: Could not perform clone using vmkernel data mover. Falling back to non-accelerated clone. Cannot allocate memory
    (and subsequent, continuous...)

    Worker#0| DISKLIB-LIB : numIOs = 2450000 numMergedIOs = 0 numSplitIOs = 0

  • The ESX host's /var/log/vmkernel log file contains an entry similar to:

    FS3DM: 1595: status Out of memory copying 16777216 bytes from file offset 0 to file offset 0, bytesTransferred = 0 extentsTransferred: 0


VMware vCenter Server 4.0.x
VMware ESXi 4.0.x Embedded
VMware ESXi 4.0.x Installable
VMware ESX 4.0.x


This issue is caused by the VMFS3-DM (Data Mover) having to use contiguous memory space on the host. When the host's kernel memory usage is greater than 50% and memory is fragmented, the destination machine cannot allocate more space and the operation fails. In the example log entries, the host has been up over 161 days.
Note: The 50% memory usage mark is not absolute. Memory use may have to be reduced well below that value.

This issue is resolved in the patch release for ESX/ESXi. For more information, see:
To workaround this issue when you do not want to apply the patch, migrate sufficient virtual machines off of the host to reduce memory consumption, or shut down non-critical virtual machines temporarily.

Additional Information

For more information on the location of log files, see Location of log files for VMware products (1021806).