Home > Storage > PowerFlex > White Papers > Deploying MySQL Database on Dell PowerFlex with NVMe over TCP > PowerFlex snapshot as a backup and recovery solution
PowerFlex snapshots are consistent block images in the form of addressable target storage volumes that capture the state of their source volumes at a specific point in time. They are thin-provisioned (do not take any additional storage capacity when created), and writable, unless you select the Secure Snapshot or Read Only options. When created, a snapshot becomes a new volume that can be managed like any other volume exposed by the storage system. When the snapshot is created with the secure snapshots option, it ensures data retention compliance by preventing alteration or deletion until a set expiration time.
Snapshots can be managed manually through the PowerFlex UI, CLI, or REST API, with automated policies available for creation, retention, and deletion according to predefined schedules. Snapshots and their source volume are organized into a Volume Tree (V-Tree). The V-Tree includes the root volume and all descendant snapshots resulting from that volume. A V-Tree includes not only snapshots taken of the root volume at different points in time, but also descendants that are snapshots of snapshots. For example, it is a common practice to create a snapshot of a production database, mask any proprietary or private data, and then create additional snapshots and provision them to groups such as Development and QA.
For more information about PowerFlex snapshots and how to use them, see the Dell PowerFlex: Snapshots Technical White Paper.
Note: Snapshots do not protect against hardware and storage system failures as the snapshots are stored on the same storage system as the original data. To protect against such failures, the organization must implement remote replication and other backup strategies to realize maximum data protection.
PowerFlex snapshots support data consistency or consistency groups. It allows you to take a snapshot of single or multiple volumes that can be selected simultaneously. All snapshots taken when you select multiple volumes from a consistency group. All snapshots in a consistency group are guaranteed to be from precisely the same point in time. They can be used to capture a crash-consistent (or storage-consistent) image across multiple volumes, making it an efficient way to create database copies.
To ensure that the database can restart from that snapshot image, the snapshot must include all the volumes holding the database datafiles, redo log files, and undo log files. When this snapshot is mapped to the target host, the MySQL service pointing to the snapshot data can be started. As a result, the database copy has all committed transactions accurately to the time that the snapshot was created. When a snapshot is taken, it can also serve for database backup and recovery as described later in this paper.
PowerFlex does not force the approach of a consistency group after it is created. The user is responsible for continuing to treat the volumes as a group for operations such as mounting them to a server, deleting them, creating additional snapshots from these volumes, and so on. To help the user with a group, a user-friendly alias can be provided while creating and restoring the snapshot.