A tape backup's size depends on the specific tape technology used, but a common modern format, LTO (Linear Tape-Open), currently holds 19 terabytes (TB) of native storage and up to 45 TB of compressed data.
Here's a breakdown:
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Native Capacity: This refers to the actual amount of data you can store on the tape without using compression. In the case of modern LTO tapes, that's 19 TB.
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Compressed Capacity: Tape drives can often compress data as it's written to the tape, effectively fitting more information onto the same physical space. The quoted "up to 45 TB" represents the maximum compressed capacity, assuming ideal conditions and highly compressible data. The actual compressed capacity will vary depending on the type of data being backed up. Some types of data (like already compressed images or video files) won't compress much at all.
Important Considerations:
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LTO Generations: LTO technology is constantly evolving. Newer generations offer increased capacity compared to older generations. For example, LTO-9 has a larger capacity than LTO-8. The 19TB/45TB figures are generally associated with LTO-9.
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Compression Ratios: The compression ratio achieved depends on the data itself. Text files typically compress well, while already compressed files (like JPEGs or MP4s) compress very little. The "up to 45 TB" figure assumes a 2.5:1 compression ratio, which may not be realistic for all data types.
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Tape Drive Compatibility: Ensure your tape drive is compatible with the generation of LTO tape you're using. An older drive might not be able to read or write to a newer, higher-capacity tape.
In summary, while the potential compressed capacity of a tape backup can be significant (e.g., up to 45TB with LTO-9), the actual usable capacity will depend on factors such as the tape generation, the type of data being backed up, and the compression capabilities of your tape drive.
