Media partitioning

There are two types of partitioning: Wrap-wise partitioning and Longitudinal partitioning (maximum 2 partitions).
Figure 1. Wrap-wise partitioning
Wrap-wise partitioning
Figure 2. Longitudinal partitioning
Longitudinal partitioning

In Wrap-wise partitioning, media can be partitioned into 1 or 2 partitions for LTO 5 and 1 - 4 partitions for TS1140. For later generations, see drive documentation for the number of partitions supported. The data partition (the default) for a single partition always exists as partition 0. WORM media cannot be partitioned.

The ioctls the device drivers provide for tape partitioning are
  • Query Partition
The Query Partition ioctl returns the partition information for the current media in the tape drive. It also returns the current active partition the tape drive is using for the media.
Note: If the Create Partition ioctl fails, then the Query Partition ioctl does not return the correct partition information. To get the correct information, the application must unload and reload the tape again.
  • Create Partition

The Create Partition ioctl is used to format the current media in the tape driver to either 1 or 2 partitions. When two partitions are created, the FDP, SDP, or IDP partition type is specified by the application. The tape must be positioned at the beginning of tape (partition 0 logical block id 0) before this ioctl is used or the ioctl fails.

If the number_of_partitions field to create in the ioctl structure is one partition, all other fields are ignored and not used. The tape drive formats the media by using its default partitioning type and size for a single partition.

When the type field in the ioctl structure is set to either FDP or SDP, the size_unit and size fields in the ioctl structure are not used. When the type field in the ioctl structure is set to IDP, the size_unit and size fields are used to specify the size for each partition. One of the two partition sizes for either partition 0 or 1 must be specified as 0xFFFF to use the remaining capacity. The other partition is created by using the size_unit and size field for the partition.

  • Set Active Partition

The Set Active Partition ioctl is used to position the tape drive to a specific partition. It becomes the current active partition for subsequent commands and a specific logical bock id in the partition. To position to the beginning of the partition, the logical_block_id field in the ioctl structure must be set to 0.