LTO 5 Speed, Capacity Lower Than Expected

Published: January 26, 2010

by Alex Woodie

New specifications were released last week for the fifth generation of the Linear Tape-Open (LTO), and it's not what we were promised. The LTO Gen 5 design calls for storing 1.5 TB of data on a single cartridge, which is almost double the storage capacity of the LTO Gen 4 specification, but less than the 1.6 TB that had been advertised. Native data transfer rates will be 140 megabytes per second, significantly less than the 180 MBPS that had been expected, and a lackluster 17 percent improvement over the 120 MBPS currently offered with LTO Gen 4 tape.

LTO is a half-inch magnetic tape format originally developed in the late 1990s by IBM, Hewlett-Packard, and Seagate as an open standards alternative to the proprietary magnetic tape formats, such as Quantum's DLT, Sony's AIT, and IBM's Magstar 3480 tape drive platforms.

Capacity and speed have steadily improved since the original LTO Gen 1 tapes, which offered 100 GB of capacity and a 15 MBPS native data transfer rate, began appearing on the market in 2000. In 2003, we were given LTO Gen 2 tapes, which offered 200 GB of capacity and data transfer rates of 40 MBPS. LTO Gen 3, which debuted in 2005, doubled capacity and speed to 400 GB and 80 MBPS, respectively. The LTO Gen 4 tape, which hit the market in 2007, doubled uncompressed capacity to 800 GB, and increased speed to 120 MBPS, a 50 percent improvement.

For the last few years, everybody has been expecting LTO Gen 5 to continue building on past performance, and to deliver a native capacity of 1.6 TB and a native data transfer rate of 180 MBPS. That would correspond with a doubling of capacity and a 50 percent increase in speed, the same improvements we saw in 2007 when we moved from LTO Gen 3 to LTO Gen 4.

Even as recently as last week, before the LTO Gen 5 specs were released, people were touting the hoped-for numbers, which are still listed on the Wikipedia listing for LTO.

But apparently, those expectations were too lofty for the magnetic reality of tape.

While the performance is not up to expectations, the LTO group has put some nifty new features into the new spec, including a new partitioning functionality that will provide new file and space management control, particularly for "rich media" formats, according to the LTO Program, which promises that more information on this "highly anticipated" technology will be available later this year.

The new LTO format also supports WORM (Write-Once, Read-Many) functionality, as every format going back to Generation 3 has. LTO Gen 5 drives are also fully read-write compatible with LTO Gen 4 cartridges, and can read LTO Gen 3 cartridges (but can't write to them).

But there was one bright spot in the tape landscape last week, and it came from IBM, which claimed its researchers made a major a breakthrough in engineering and design for half-inch magnetic tape. According to IBM, several new technologies and techniques have come together to allow for a single cartridge to hold 35 TB of uncompressed data. You can read the entire story in this week's The Four Hundred: "IBM Claims Major Breakthrough in Tape Density".