MediaAgents can write to media using different block sizes if the operating system and the hardware (HBA) that is associated with the MediaAgent on which the library is configured supports a higher block size. Increasing the block size increases the speed of write operations to tape media.
For mount paths, block size is the buffer size used for each write operation. (The File system allocation unit size is decided when the volume is formatted.)
Ensure the following, before increasing or making changes to the block size:
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Confirm all MediaAgent environments that write to tape, including File Servers and Disaster Recovery sites, support the new block size.
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New block size is supported by the Host Bus Adapter Driver installed in the MediaAgent and the tape device. The most commonly used values are 128 KB or 256 KB.
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All the MediaAgents that are associated with a Storage Policy support the block size that is configured on that storage policy
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If different MediaAgents are used for backup and restore operations, and the backup MediaAgent has higher block size, then ensure that the restore MediaAgent is configured with Host Bus Adapters, and that tape drives that are able to read the data written with higher block size.
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If you want to modify the block size, use the following supported values of block size:
MediaAgent
Supported Block Size
Related Topic
ONTAP 6.5 NetApp Appliances
64 KB or lower
Dell EMC VNX/Celerra 5.3 filers
128 KB or lower
Can Dell EMC VNX / Celerra NDMP backups to a file-server-attached tape use a 256 KB block size?
Block sizes can be modified from the Data Path Properties dialog box available from the Data Paths tab of the Copy Properties dialog box, for the specific data path.