Non-disruptive storage server migration

Abstract

The techniques introduced here provide a storage server migration that is non-disruptive to client applications. The techniques described here allow the migration of data from a source storage server to a destination storage server without the need for planned downtime typically associated with storage server migration. Using the techniques described here, data migration operations are performed while client applications continue to run and access data from the source storage server. Once data migration operations are complete, all applications and clients are transitioned to the destination storage server without disruption to the client applications.

1 . A method for non-disruptive migration of a storage server, comprising:
 creating a baseline copy of a source storage server, including storage server configuration information, on a destination storage server, wherein a client application has data access to the source storage server;   mirroring data written to the source storage server, on the destination storage server, in response to the data being written to the source storage server; and   performing a migration from the source storage server to the destination storage server without reconfiguring the client application prior to the client application accessing data from the destination storage server.   
     
     
         2 . The method of  claim 1  wherein the source storage server and the destination storage server are virtual storage servers. 
     
     
         3 . The method of  claim 1 , wherein performing a migration includes stopping data access and administrative access to the source storage server without disruption to the client application during a cutover period. 
     
     
         4 . The method of  claim 3  further comprising monitoring the source storage server and the destination storage server during the cutover period to determine whether the migration will be successfully completed within an allotted non-disruptive time limit for the cutover period, wherein in response to a determination that a successful migration will not be successfully completed, data access and administrative access are restored to the source storage server. 
     
     
         5 . The method of  claim 4  wherein the allotted non-disruptive time limit for the cutover period is less than or equal to a protocol timeout period. 
     
     
         6 . The method of  claim 5  wherein performing a migration further includes the source storage server unbinding a first storage address and the destination storage server configuring a second storage address during the cutover period, wherein the second storage address configured at the destination storage server is the same as the first storage address unbound from the source storage server. 
     
     
         7 . The network storage system of  claim 6 , wherein performing a migration further includes initiating data access and administrative access to the destination storage server, without client side reconfiguration, upon completion of the cutover period. 
     
     
         8 . The method of  claim 1  wherein reconfiguring the client application includes restarting the client application and configuring storage addresses. 
     
     
         9 . A network storage system comprising:
 a source storage server including a plurality of data volumes;   a destination storage server; and   wherein the source storage server and the destination storage server are configured to perform a migration of the plurality of data volumes and access to the plurality of data volumes from the source storage server to the destination storage server, wherein the migration occurs without reconfiguring a client application prior to accessing data from the destination storage server.   
     
     
         10 . The network storage system of  claim 9 , wherein the source storage server and the destination storage server are virtual storage servers. 
     
     
         11 . The network storage system of  claim 9 , wherein the migration includes the source storage server and the destination storage server monitoring during a cutover period to determine whether a successful migration will complete within an allotted non-disruptive time limit for the cutover period. 
     
     
         12 . The network storage system of  claim 11 , wherein the allotted non-disruptive time limit for the cutover period is less than or equal to a protocol specified timeout period. 
     
     
         13 . The network storage system of  claim 12 , wherein the migration further includes transferring an storage address from the source storage server to the destination storage server during the cutover period. 
     
     
         14 . The network storage system of  claim 13 , wherein the migration further includes stopping data access and administrative access to the source storage server during the cutover period without disruption to the client application. 
     
     
         15 . The network storage system of  claim 14 , wherein the migration further includes resuming data access and administrative access to the source storage server in response to a determination that a successful migration will not be completed within the allotted non-disruptive time limit for the cutover period. 
     
     
         16 . The network storage system of  claim 15 , wherein the migration further includes initiating data access and administrative access to the destination storage server, without client side reconfiguration, upon completion of the cutover period. 
     
     
         17 . The network storage system of  claim 9  wherein reconfiguring the client application includes restarting the client application and configuring storage addresses. 
     
     
         18 . A method for non-disruptive migration of a storage server, comprising:
 creating a copy of data from a source storage server on a destination storage server while maintaining client data access and administrative access to the source storage server;   mirroring data written to the source storage server, on the destination storage server, in response to the data being written to the source storage server;   stopping data access and administrative access to the source storage server without interrupting operation of client applications, in response to the data on the source storage server and the destination storage server reaching a synchronized state; and   monitoring a cutover period to determine whether a migration will complete within an allotted non-disruptive time limit for the cutover period;
 wherein, in response to a determination that a migration will not complete within the allotted non-disruptive time limit, restoring data access and administrative access to the source storage server; and 
 wherein, in response to a determination that a migration will complete within the allotted non-disruptive time limit, initializing the destination storage server to begin serving data and initiating data access and administrative access to the destination storage server without client side reconfiguration. 
   
     
     
         19 . The method of  claim 18  wherein the source storage server and the destination storage server are virtual storage servers. 
     
     
         20 . The method of  claim 18  wherein initializing the destination storage server comprises releasing a first storage address from the source storage server and configuring a second storage address to the destination storage server, wherein the second storage address configured at the destination storage server is the same as the first storage address released from the source storage server. 
     
     
         21 . The method of  claim 18  wherein the allotted non-disruptive time limit for the cutover period is less than or equal to a protocol specified timeout period. 
     
     
         22 . A network storage server system comprising:
 a source storage server and a destination storage server, each including:   a network interface through which to communicate with a client application over a network;   a storage interface through which to communicate with a nonvolatile mass storage subsystem; and   a processor configured to cause the network storage server system to perform a plurality of operations, including:
 transferring a copy, including storage server configuration information, of the mass storage subsystem of the source storage server from the source storage server to the destination storage server, wherein the client application continues to access data from the source storage server; 
 mirroring data written to the source storage server, on the destination storage server, in response to the data being written to the source storage server; and 
 performing a cutover from data access and administrative access provided by the source storage server to data access and administrative access provided by the destination storage server without interrupting operation of the client application. 
   
     
     
         23 . The network storage server system of  claim 22 , wherein the source storage server and the destination storage server are virtual storage servers. 
     
     
         24 . The network storage system of  claim 22 , wherein the plurality of operations further includes monitoring the source storage server and the destination storage server during a cutover period to determine whether a successful migration will complete within an allotted non-disruptive time limit for the cutover period. 
     
     
         25 . The network storage system of  claim 24 , wherein the allotted non-disruptive time limit for the cutover period is less than or equal to a protocol specified timeout period. 
     
     
         26 . The network storage system of  claim 25 , wherein the plurality of operations further includes transferring an storage address from the source storage server to the destination storage server during the cutover period. 
     
     
         27 . The network storage system of  claim 26 , wherein the plurality of operations further includes resuming data access and administrative access to the source storage server when a successful migration will not be completed within the allotted non-disruptive time limit for the cutover period.