Tape Cartridge Capacity is Displayed Incorrectly

Product version: 11.0

Last modified: 26 August 2025

Question

Why does the capacity displayed on the tape device appear larger than its actual size shown in NAKIVO Backup & Replication?

Answer

NAKIVO Backup & Replication displays tape capacity based on the information reported by the tape drive, which may include hardware compression. Native capacity is the actual storage a tape can hold without compression (for LTO-6, this is 2.5 TB). Compressed capacity assumes hardware compression and can increase effective storage, typically using a 2.5:1 ratio—so an LTO-6 tape may display up to 6.25 TB. When hardware compression is enabled, NAKIVO may show total, used, and free space based on compressed capacity, making the tape appear to hold 2–2.5 times more data than its native size. For accurate planning, always consider the native capacity when calculating tape usage. See also LTO Specifications.

Notes:

• Compressed capacity is theoretical and assumes ideal data compressibility. Backup files are often already compressed or deduplicated, so actual compression may be lower.

• Marketing labels (e.g., “6.25 TB LTO-6”) reflect maximum compressed capacity, not native size.