Tuning GNU Tar's buffer option can greatly improve tape write performance for VXA-3 and perhaps other tape drives.

Problem

Backups to tape can be so slow that they exceed their nightly time window.

Hypothesis

Using Tar's buffer size option the data stream from Tar to the tape drive could be optimized. This would increase speed.

Create a 256 MB file using:
dd if=/dev/zero of=tartest bs=10k count=26200
Copy time the Tar process as it writes the test file to tape.
time tar -b x -cf /dev/st0 tartest
Where x is the buffer size.

**Figure 1:** Tar speed test with VXA-320 tape drive

A buffer beyond 1024 offered no performance gain.

Tuning the buffer size can offer significant performance gains in backup times. Try this with your own tape drives.

Tuning VXA-3 Performance in Linux

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The translation was initiated by Neil Watson on 2006-09-01

Neil Watson 2006-09-01