Disk Libraries - Best Practices
Once you configure a disk library, we recommend that you perform or schedule frequent Auxiliary Copy operations to a secondary storage such as tape media. This will ensure that you have a copy of the backup data in case of disk failure.
Defining Mount Paths
You can define one or more mount paths to local or remote computers for Windows and UNIX file systems. You cannot define mount paths to a disc drive, for example, CD-ROM drive, or a locally mapped network drive.
If the mount path directory does not exist, it is automatically created when you add the mount path.
If you have defined multiple mount paths for a disk library, the system determines the specific path to which data secured by a data protection operation is written.
Using Dedicated Partitions
Use dedicated partitions for your disk mount paths to ensure that the MediaAgent always accesses the mount paths allocated to disk libraries:
We recommend the following practices for creating mount paths:
- Do not create a mount path on the same partition where the MediaAgent software is installed.
- Do not create a mount path under an already existing CV_MAGNETIC folder.
Storage Space for Mount Path
Make sure that each mount path contains at least 2 GB of free space when it is created, and that the total storage space in the disk library is sufficient to hold the maximum amount of data that will be stored in the library at any time.
Using a UNC Path as a Mount Path
If you want to use a path to a remote Windows computer as a mount path, the mount path must follow the Universal Naming Convention (UNC), with the following format:
\\<computer name>\<shared directory name>\<optional path>
The remote computer can belong to the same domain as the MediaAgent from which it is accessed, or to a different domain, provided that a trust has been set up between that domain and the MediaAgents domain.
When a mount path is created using UNC paths, verify and ensure that the user account used to access the mount path has sufficient permissions to read / write in the software install folder on the computer where the MediaAgent that is associated with mount path is installed. The MediaAgent uses these folders to create the required log entries in the log files for jobs that are associated with the mount path.
The mount path for a disk library in a clustered environment should be a UNC path or the shared disk on a cluster.
Mount Path to a Remote UNIX Computer
An NFS mounted file system can be used as a mount path to a remote UNIX computer. The system considers an NFS mounted file system local to the computer where it is mounted.
Accessing Mount Paths
The software does not permit the creation of two mount paths that access the same directory. This is true even if one mount path accesses the directory locally while another mount path accesses it remotely.
Mount Path Is Marked as Offline
If a disk volume in Windows platform is found to be dirty, the volume is marked offline. Any attempts to access the volume will result in error. Clean up the volume and manually bring it back online.
If a mount path directory is deleted or renamed (that is, through the operating system), it is not recreated the next time a data protection operation attempts to accesses the mount path. The mount path becomes inaccessible for the job and hence the mount path is marked as offline. Attempts to back up to that mount path will generate error messages.
Maximum Number of Writers
The maximum number of writers for a disk library is used to determine the maximum number of concurrent write operations. Hence this value is linked to the maximum number of data streams that can be established for a storage policy accessing the disk library.
The values for writers can be modified from the Disk Library Properties and Mount Path Properties dialog box available in the CommCell Console. The values for the maximum number of data streams can be modified from the Storage Policy Properties dialog box also available in the CommCell Console.
Storage Policy Data Streams
Storage Policy data streams are logical channels that connect client data to the media where the data that is secured by data protection operations is stored. Multiple data streams can be used to run an operation simultaneously to improve the rate at which data can be written to the media.
The practical limits for establishing data streams in a storage policy that accesses a disk library is determined by the minimum value established in either the disk library or the sum of mount paths in the disk library.
You can enable the disk spin-down feature, which is a power saver mode depending on your particular setup. You may consult the hardware vendor to verify if the disk spin-down feature is enabled or disabled on your disk array if you are experiencing data access or throughput delay.