How to use the command 'virsh pool-start' (with examples)

The virsh pool-start command is a utility part of the Virtual Machine Manager (libvirt) suite, designed to manage virtualization environments. This particular command focuses on starting storage pools that have been previously defined but are currently inactive. A storage pool is a set of storage volumes that you can allocate to virtual machines. The virsh pool-start command enables you to activate these pools, ensuring they are ready to provide storage resources when needed. This command can be used in conjunction with others like virsh-pool-define-as for defining pools initially and virsh-pool-destroy for stopping them.

Use case 1: Starting and building a storage pool by specifying its name or UUID

Code:

virsh pool-start --pool name|uuid --build

Motivation:

In a virtualized environment, maintaining efficient storage management is critical. Sometimes, you have pre-configured storage pools that are inactive and need to be started for use with virtual machine instances. Additionally, the underlying storage infrastructure might need to be set up before you can utilize these pools effectively. In such scenarios, using the virsh pool-start command with the --build option becomes essential as it not only activates the pool but also ensures that the underlying storage system is created if it doesn’t already exist. This is particularly useful in cloud computing environments or data centers where storage configurations might change or need reactivation after system restarts or maintenance operations.

Explanation:

• virsh: This is the command-line interface for managing virtual machines and associated resources using libvirt.
• pool-start: This command is specifically used to start an inactive storage pool.
• --pool: This option allows you to specify the storage pool you want to operate on, using either its name or UUID.
• name|uuid: Represents the actual identifier of the storage pool, which can be either the pool’s name or its unique identifier (UUID). You can find these details using virsh pool-list.
• --build: This flag tells the command to also create any necessary underlying storage infrastructure if it doesn’t already exist. It ensures that the pool is not only started but also fully prepared for operations.

Example Output:

Pool <name|uuid> started

Building storage pool <name|uuid>
Pool <name|uuid> completed successfully

In this output, the system informs you that the specified storage pool has been successfully started and that the necessary underlying storage was built without issues. This indicates the storage pool is now ready for allocation and use by virtual machines.

Conclusion:

The virsh pool-start command is an integral utility for managing storage pools within a virtualized environment. By starting a previously inactive storage pool, you ensure that your virtual machine resources have adequate storage resources to function optimally. The ability to build the underlying storage as part of starting the pool adds a layer of convenience, automatically setting up the necessary infrastructure. This command thus aids in effective resource management, providing a seamless way to manage storage infrastructure in virtualized settings comprehensively.