Specifications

VMware, Inc. 279
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In!this!chapter,!the!following!sections!describe!how!to!use!VMware!ESX!Server!to!
provide!clustered!virtual!machines!in!a!variety!of!environments.
! “What!Is!Clustering?”!on!page 279
! “Clustering!Virtual!Machines”!on!page 280
! “Network!Load!Balancing”!on!page 302
What Is Clustering?
Clustering!provides!a!service!through!a!group!of!servers!to!get!high!availability,!
scalability,!or!both.
For!example,!all!nodes!in!a!cluster!serve!a!Web!site!that!serves!static!content.!The!main!
gateway!distributes!requests!to!all!nodes!according!to!load.!It!redirects!requests!to!
remaining!nodes!if!one!crashes.!
This!gives!better!availability!and!better!performance.!
Network!Load!Balancing!in!Windows!2000!provides!such!a!service.!
Another!example!of!a!more!complex!configuration:!A!single!node!serves!a!database.!If!
that!node!crashes,!the!clustering!software!must!restart!the!database!on!another!node.!
The!database!application!knows!how!to!recover
!from!a!crash.!In!normal!operation,!
other!nodes!are!used!for!running!other! applications.!Microsoft!Cluster!Service!and!
Veritas!Cluster!Service!provide!such!a!service.
Configuration for Clustering
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