Use this dialog box to view or modify the usage properties for the mount path of a disk library.
Mount Path Allocation Policy
-
Maximum Allowed Writers
When selected, maximum number of concurrent writers on the mount path will be established.
-
Allocate number of Writers
By default, maximum concurrent writers are established on the mount path. To limit the number of writers, type the number of writers that you want to allocate.
-
Disable mount path for new data
Specifies that new write operations are not allowed on the mount path. However, read and prune operations can be performed.
Prevent data block references for new backups
When selected, the deduplicated blocks in the mount path will not be referenced when there are multiple mount paths in the library. (Choose this option if you plan to retire the mount path.)
Space Allocation
-
Reserve Space (GB)
Specifies the total amount of free space that must be available at all times when the system writes data to the mount path. You can change this value to modify the amount of free space. The smallest value that you can enter is 2 GB.
The default values are as follows:
-
For most mount paths, the reserve space is 2% of the total capacity of the mount path or 100 GB, whichever is smaller.
-
For mount paths associated with HyperScale storage pools, the reserve space is 4% of the total capacity of the mount path.
-
-
Use until free space on mount path reaches Reserved Space
Specifies that the entire mount path minus the reserve space is used to store valid data.
-
Do not consume more than n GB
When this option is selected, the system writes data up to the amount that you specify. However, if that amount is greater than the reserve space allows, the system stops writing data when the reserve space is met, regardless of the amount that you specify for this option.
For example, if you specify 8 GB as the amount for this option, but the space on the mount path is 10 GB and the reserve space is 4 GB, the system stops writing data to the mount path once 6 GB is reached.
Note
The system deducts both the Reserve Space and Do not consume more than n GB values from the FreeSpace, and considers the lesser value after deduction as the Usable Free Space available in the mount path. To view the Usable Free Space in libraries, from the CommCell Browser, expand Storage Resources > Libraries. To view the Usable Free Space in libraries associated with a specific MediaAgent, from the CommCell Browser, expand Storage Resources > MediaAgents > MediaAgent.
Fragmentation
-
Minimize fragmentation by allocating write blocks of n MB
This option allows the MediaAgent to preallocate a specified portion of the backup chunk before beginning a write operation. The chunk size should be determined based on the disk array and the file allocation unit size.
Preallocating a specified chunk size before the write operation enables the Operating System to allocate contiguous disk clusters based on the requested chunk size, thus reducing disk fragmentation. This option is supported on Windows MediaAgent. For additional information on determining the chunk size, see CommCell Performance Tuning - Increasing Chunk Size.
Pruning
-
Enable Pruning of Aged Data
By default, pruning is enabled. To prevent pruning of aged data, clear the check box.
-
Select MediaAgents for pruning aged data based on the associated copy's datapath
By default, pruning request is sent to any MediaAgent that has access to the library, irrespective of whether the MediaAgent is part of the datapath or not.
Select this check box to send the pruning request to only those MediaAgents associated with the datapaths in the Storage Policy copy.