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VMware ESX General Information

April 21st, 2008 No comments

The main difference between ESX and regular VMware server is that ESX runs its own VMware kernel (loaded with GRUB) and allows for the virtualization technology to live closer to the hardware. VMFS, available in ESX, allows for larger files and offers higher performance over traditional file systems like EXT3. VMFS is tuned for large files and exhibits almost raw filesystem speed.

Key Terms
H.A - High Availablity
VMotion - Move live guest to different hosts in real-time
DRS - Distributed Resource Scheduler - allows for distributed resource management
VMFS - Large file support, provides near raw disk speeds

The ESX console is simply another virtual machine which has access to the VMKernel (through hostd process) and allows for management of the host. This console provides SNMP monitoring and all management functions for manipulating guests and the host configuration.

Networking

  • Default of 56 ports per virtual switch. Maximum of 1016 (8 reserved for trunking)
  • Three types of network connections.
    • Service console port (should be bonded)
    • VMkernel port - access to VMotion, iSCSI and NFS traffic traverses this port or portgroup
    • Virtual machine port group - access to VM networks
  • Creating Virtual Switches (Very simple)
  • Console command "esxcfg-nics -l" lists all NICs available on the host machine
  • Three methods of load distribution
    • Port-Based
             VMKernel decides which physical NIC will carry the packet to the outside world. This method does not require special switch configuration. This method
    • Source MAC-Based
             VMKernel maps VM to physical adaptors based on the source MAC hash. This method has low overhead but might not effectively spread the load to all physical adapters.
    • IP-Based
             VMKernel routes outbound and inbound traffic based on IP address. This requires VMKernel to inspect packets at Layer-3 and can introduce more CPU overhead and might not be the best option for high-throughput applications.
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