How do I speed up backups to DLT tapes?

[an error occurred while processing this directive]

How do I speed up backups to DLT tapes?

DLT tapes need high data rates to stay in streaming mode. To achieve
higher data rates, use a variable length block size by setting the fixed
length block size to zero. Also use a buffer size of about 64KB for
backup (128 blocks for tar).

[an error occurred while processing this directive]