Fail over method through disk take over and computer system having fail over function

For use in a computer system comprising a plurality of servers which are connected to an external disk device via a network and each of which can be started by booting an operation system from said external disk device;

• and a management server comprising a partition management module which makes each of the plurality of servers belong to one of a plurality of logical partitions, each of which is composed of one or more servers, and which allows the servers belonging to one logical partition to work as one logical server, a fail over method for taking over task processing from a primary server to some other server when said primary server executing a task fails, said method comprising:
• a detection step of detecting that said primary server fails;
• a first search step of searching the servers in said computer system for a set of servers that is not executing a task and that currently configures a logical partition with the same configuration as that of a logical partition to which said primary server belongs;
• a configuration step of configuring a standby logical partition composed of the set of servers searched for as a results of said first search step;
• an enabling step of enabling each server of the set of servers, searched for as a result of the search, to access said external disk device;
• and
• a booting step of booting each of servers of the set of servers, which is searched for, from said external disk device.

For use in a computer system in which a plurality of servers are connected to an external disk device via a network and each of said servers can be started by booting an operation system from said external disk device, a fail over method for taking over task processing in said computer system from a primary server to some other server when said primary server executing a task fails, said method comprising the steps of:

• registering a priority of a task, executed in each of said plurality of servers, in a management table;
• upon detecting that said primary server fails, referencing said management table for searching for a server executing a task whose priority is lower than that of a task executed by said primary server;
• and
• taking over the task executed by said primary server to the server searched for as a result of the search.

For use in a computer system in which a plurality of servers are connected to an external disk device via a switch by which a plurality of virtual networks can be built and each of said servers can be started by booting an operation system from said external disk device, a fail over method for taking over task processing from a primary server to some other server in said computer system when said primary server executing a task fails, said method comprising the steps of:

• detecting that said primary server fails;
• searching the servers in said computer system for a server that will take over said primary server under a search condition that the server is not running a task and has the same hardware configuration as that of said primary server;
• and
• changing a setting of said switch so that the server searched for by said search belongs to the same virtual network as that of said primary server.

A computer system comprising:

• a plurality of servers which are connected to an external disk device via a network and each of which can boot an operation system from said external disk device;
• and
• a management server that manages said plurality of servers, wherein said management server comprises a fail over module comprising:
• a server management table in which hardware configurations of said plurality of servers are recorded;
• server search means for searching for a server that, when a primary server that is one of the servers and that is executing a task fails, takes over said primary server under a condition that said server is not executing a task and has the same hardware configuration as that of said primary server;
• and
• mapping change means for requesting said external disk device to map external disks used by said primary server to the server searched for by said server search means.

A computer system comprising:

• a plurality of servers which are connected to an external disk device via a network and each of which can be started by booting an operation system from said external disk device;
• a logical partition module which makes each of the plurality of servers belong to one of a plurality of logical partitions, each of which is composed of one or more servers, and which allows the servers belonging to one logical partition to work as one logical server;
• and
• a management server that manages the plurality of servers, wherein said management server comprises a fail over module comprising:
• a server management table in which hardware configurations of said plurality of servers are recorded;
• server search means for searching for a server that, when a primary server that is one of the servers and that is executing a task fails, takes over said primary server under a condition that said server is not executing a task and has the same partition configuration as that of said primary server;
• and
• mapping change means for requesting said external disk device to map external disks used by said primary server to the server searched for by said server search means.