Tape devices use magnetic tape media to store information and can be divided into 3 type:
- Standalone tape drives. Here one tape cartridge can be inserted into the device and used. To write or read data from other tape cartridge, the previous tape has to be ejected and taken out from the drive first.
- Tape library is a device that apart from a tape drive (one or more) has also additional slots to store tape cartridges. Via the device or third-party software interface tapes can be moved between slots and drives. A slot that allows inserting new tapes and ejecting tapes is called mail slot. Tapes in tape libraries usually have unique barcodes which can be optically read by the reader during inventory. The barcode duplicates the information stored in tags placed in the beginning of the tape data.
- Virtual tape library (VTL) is a storage virtualization technology, that allows the representation of a storage device as a tape library or a tape drive. Usually is it used to represent a hard disk storage device as a tape library, in a special case an RDX device.
When speaking of tape types, LTO is a major standard and the version of the LTO tape cartridge defines its characteristics including capacity. Modern generation LTO-3 and LTO-4 come with HDD competitive read/write speed of 80 and 120 MB/s and capacity of 400 GB and 800 GB respectively.
Tapes are storage media that can only be read sequentially as opposed to HDDs, and per ABR tape vault format we can only add something to the free end of the tape, but we cannot re-write a part of the tape and place new information keeping some piece of previous information. Tape will always be overwritten completely.