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VMware ESX Server 3.0.3, ESX303-200901401-BG: COW_MAX_HEAP_SIZE_MB parameter Can be Changed Only in Service Console; ESX Server Fails When a Guest Operating System Sends a Large Data Packet with Large Number of Scatter Gather Elements (1007677)


Release Date: 01/30/09
Document Last Updated: 01/30/09

136 MB
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Product Versions ESX Server 3.0.3
Patch Classification Critical

ESX303-200811401-BG, ESX303-200901402-SG

Virtual Machine Migration or Reboot Required Yes
ESX Server Host Reboot Required Yes
PRs Fixed 296024, 353373
Affected Hardware None
Affected Software e1000 virtual NIC
RPMs Included VMware-esx-apps, VMware-esx-vmkctl, VMware-esx-vmkernel, VMware-esx-vmx, VMware-hostd-esx  
Related CVE numbers N/A



This patch fixes the following issues:

  • In systems without this patch, the value of COW_MAX_HEAP_SIZE_MB parameter is changed through the VI Client (Configuration > Advanced Setting > COW > MaxHeapSizeMB) or running the following command from the service console: esxcfg-advcfg –s <val> /COW/MaxHeapSizeMB

    After installing this patch, the value of COW_MAX_HEAP_SIZE_MB parameter can be changed by running the following command in the service console:

    esxcfg-advcfg -k <val> cowMaxHeapSizeMB

    The constraints of COW_MAX_HEAP_SIZE_MB parameter are:

Minimum: 40

Maximum: 192

Default: 40

The value of COW_MAX_HEAP_SIZE_MB parameter can be queried by running the following command:

esxcfg-advcfg -j cowMaxHeapSizeMB

  • In some cases, a guest operating system using the e1000 virtual NIC can send packets with unusually large number of scatter gather elements. VMkernel does not handle such packets gracefully and fails. This fix enables the VMkernel to gracefully drop such packets instead of failing.

Deployment Considerations


Patch Download and Installation

Note: All virtual machines on the host must be either shut down or migrated using VMotion before applying the patch. A reboot of the ESX Server host is required after applying this patch.
See the VMware Update Manager Administration Guide for instructions on using VMware Update Manager to download and install patches to automatically update ESX Server 3.0.3 hosts.

To update ESX Server 3.0.3 hosts when not using VMware Update Manager, download the most recent patch bundle from and install the bundle using esxupdate from the command line of the host. For more information, see the ESX Server 3 Patch Management Guide .

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


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