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As everyone already know, tape winds between BOT and EOT when reading/writing data in the same LTO partition.

But what if a tape drive read data in different partitions? Will it move across wraps in a tape (similar to a printer head)? or it can just "focus on" one wrap without moving?

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Tape does not move during the partition change. Only the drive head physically moves.
Once the seek operation is performed on the partition, the tape will move.

Guard wraps separate partitions. During the partition change, the head has to "jump over" the guard wrap to reach different partition.

LTO Tape Partition Layout

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  • Does drive head movement causes significant read/write latency? – petertc May 22 '18 at 5:11
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    Drive head movement latency is negligible comparing to the average tape positioning time. – Andi May 22 '18 at 7:22
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Partitions are using physically distinct locations on the tape - reading from alternate partitions requires the tape to move accordingly.

The intention behind LTO partitioning is the use of LTFS where one partition holds the metadata and the other the file data. The metadata partition is read to a host buffer in total when mounting the tape and written back in total when dismounting the tape, so there's no need to skip back while read/writing files.

If you use the partitions in another way you need to make sure you don't shoeshine the tape.

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