System and Method for Managing Size of Clusters in a Computing Environment

Abstract

A number of hosts in a logical cluster is adjusted up or down in an elastic manner by tracking membership of hosts in the cluster using a first data structure and tracking membership of hosts in a spare pool using a second data structure, and upon determining that a triggering condition for adding another host is met and that all hosts in the cluster are being used, selecting a host from the spare pool, and programmatically adding an identifier of the selected host to the first data structure and programmatically deleting the identifier of the selected host from the second data structure.

We claim: 
     
         1 . In a data center comprising a cluster of hosts, a spare host pool, and a failed host pool, a method of adjusting the number of hosts in the cluster, comprising:
 tracking membership of hosts in the cluster using a first data structure;   tracking membership of hosts in the spare host pool using a second data structure;   tracking membership of hosts in the failed host pool using a third data structure;   determining that the cluster does not include a sufficient number of operable hosts based on determining that an availability of one or more virtual machines (VMs) on a first host in the cluster;   selecting a second host from the spare host pool;   adding an identifier of the selected second host to the first data structure;   migrating the VM from the first host to the second host;   adding an identifier of the first host to the third data structure; and   deleting the identifier of the first host from the first data structure.   
     
     
         2 . The method of  claim 1 , wherein determining that the cluster does not include a sufficient number of operable hosts is based on determining the existence of a partial or total failure of the first host in the cluster. 
     
     
         3 . The method of  claim 1 , wherein the VM is migrated from the first host to the second host upon a failure of the first host. 
     
     
         4 . The method of  claim 1 , further comprising:
 copying data locally stored in the first host to a storage device accessible by the cluster.   
     
     
         5 . The method of  claim 1 , wherein the VM is migrated from the first host to the second host when an average resource utilization in the first host is greater than an upper threshold utilization. 
     
     
         6 . The method of  claim 5 , wherein the resource is CPU or memory. 
     
     
         7 . The method of  claim 6 , further comprising:
 copying data locally stored in a host with the lowest resource utilization to a storage device accessible by the cluster.   
     
     
         8 . A non-transitory computer-readable medium comprising instructions that are executable in a computing device to cause the computing device to at least:
 track membership of hosts in the cluster using a first data structure;   track membership of hosts in the spare host pool using a second data structure;   track membership of hosts in the failed host pool using a third data structure;   determine that the cluster does not include a sufficient number of operable hosts based on determining that an availability of one or more virtual machines (VMs) on a first host in the cluster;   select a second host from the spare host pool;   add an identifier of the selected second host to the first data structure;   migrate the VM from the first host to the second host;   add an identifier of the first host to the third data structure; and   delete the identifier of the first host from the first data structure.   
     
     
         9 . The non-transitory computer-readable medium of  claim 8 , wherein determining that the cluster does not include a sufficient number of operable hosts is based on determining the existence of a partial or total failure of the first host in the cluster. 
     
     
         10 . The non-transitory computer-readable medium of  claim 8 , wherein the VM is migrated from the first host to the second host upon a failure of the first host. 
     
     
         11 . The non-transitory computer-readable medium of  claim 8 , wherein the instructions further cause the computing device to copy data locally stored in the first host to a storage device accessible by the cluster. 
     
     
         12 . The non-transitory computer-readable medium of  claim 8 , wherein the VM is migrated from the first host to the second host when an average resource utilization in the first host is greater than an upper threshold utilization. 
     
     
         13 . The non-transitory computer-readable medium of  claim 12 , wherein the resource is CPU or memory. 
     
     
         14 . The non-transitory computer-readable medium of  claim 13 , wherein the instructions cause the computing device to copy data locally stored in a host with the lowest resource utilization to a storage device accessible by the cluster. 
     
     
         15 . A system of computers, comprising:
 a cluster of hosts;   a spare pool of hosts; and   a management server configured to:
 track membership of hosts in the cluster using a first data structure; 
 track membership of hosts in the spare host pool using a second data structure; 
 track membership of hosts in the failed host pool using a third data structure; 
 determine that the cluster does not include a sufficient number of operable hosts based on determining that an availability of one or more virtual machines (VMs) on a first host in the cluster; 
 select a second host from the spare host pool; 
 add an identifier of the selected second host to the first data structure; 
 migrate the VM from the first host to the second host; 
 add an identifier of the first host to the third data structure; and 
 delete the identifier of the first host from the first data structure. 
   
     
     
         16 . The system of  claim 15 , wherein determining that the cluster does not include a sufficient number of operable hosts is based on determining the existence of a partial or total failure of the first host in the cluster. 
     
     
         17 . The system of  claim 15 , wherein the VM is migrated from the first host to the second host upon a failure of the first host. 
     
     
         18 . The system of  claim 15 , further comprising copying data locally stored in the first host to a storage device accessible by the cluster. 
     
     
         19 . The system of  claim 15 , wherein the VM is migrated from the first host to the second host when an average resource utilization in the first host is greater than an upper threshold utilization. 
     
     
         20 . The system of  claim 19 , wherein the resource is CPU or memory.