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Chapter 25. Storage concepts

25.1. Storage pools
25.2. Volumes
This chapter introduces the concepts used for describing managing storage devices.
Local storage
Local storage is directly attached to the host server. Local storage includes local directories, directly attached disks, and LVM volume groups on local storage devices.
Networked storage
Networked storage covers storage devices shared over a network using standard protocols. Networked storage includes shared storage devices using Fibre Channel, iSCSI, NFS, GFS2, and SCSI RDMA protocols. Networked storage is a requirement for migrating guest virtualized guests between hosts.

25.1. Storage pools

A storage pool is a file, directory, or storage device managed by libvirt for the purpose of providing storage to virtualized guests. Storage pools are divided into storage volumes that store virtualized guest images or are attached to virtualized guests as additional storage.
libvirt uses a directory-based storage pool, the /var/lib/libvirt/images/ directory, as the default storage pool. The default storage pool can be changed to another storage pool.
Storage pools can be divided up into volumes or allocated directly to a guest. Volumes of a storage pool can be allocated to virtualized guests. There are two categories of storage pool available:
Local storage pools
Local storage pools are directly attached to the host server. Local storage pools include local directories, directly attached disks, and LVM volume groups on local devices.
Local storage pools are useful for development, testing and small deployments that do not require migration or large numbers of virtualized guests. Local storage pools are not suitable for many production environments as local storage pools do not support live migration.
Networked (shared) storage pools
Networked storage pools covers storage devices shared over a network using standard protocols.
Supported protocols for networked storage pools:
  • Fibre Channel-based LUNs
  • iSCSI
  • NFS
  • GFS2
  • SCSI RDMA protocols (SCSI RCP), the block export protocol used in Infiniband and 10GbE iWARP adapters.
Networked storage is a requirement for migrating guest virtualized guests between hosts. Networked storage pools are managed by libvirt.