The New Generation of SDLT and LTO
Data Storage Drives and Tapes
Storage Area Networks (SANs) have created a new era in data backup functionality by providing on-line tape data storage (as opposed to off-line storage – meaning the data storage tape is not connected to the IT infrastructure). Implementing an automated tape library on a SAN improves the backup options and availability as well as enhancing backup reliability, flexibility and performance. A SAN tape library can be shared across multiple servers, reducing the cost of dedicated libraries and removing backup traffic on networks. SAN-based backup is also critical to reducing storage management costs by allowing backup operations to be consolidated and managed centrally.
However, the challenge is tape technology meeting the demands of current storage and backup needs. Modern enterprise IT environments require 24/7, 365 day a year functionality, and the improved Super Digital Linear Tape (SDLT) and Linear Tape-Open (LTO) Ultrium drives and tapes have been enhanced to meet these requirements.
Improved Durability and Reliability
From the actual recording media to a variety of other enhancements, SDLT and LTO Ultrium each provide a durable and reliable tape technology that can handle the demands of SAN tape backup.
Quantum's Superloader drives and HP’s StorageWorks Ultrium 460 LTO drives have dramatically improved reliability and reach 250,000 hours MTBF at a 100% duty cycle. For the tapes themselves, the LTO Ultrium 2 and Advanced Metal Powder-based SDLT media can reach 1,000,000 head passes with life expectancy of more than 30 years. Improvements in cartridges, head design, servo design, encoding, and track densities all contribute to making tape storage a feasible part of the SAN.
Improvements in the SDLT and LTO servo positioning mean that accurate reading and writing occurs even at very high track densities. While SLDT and LTO use very different positioning techniques, both have enhanced capability.
LTO uses an embedded tracking guide on the media itself to position the heads properly on the tracks. The SDLT, which has the technical advantage of single manufacturer as opposed to the licensed “open” technology of LTO, achieves excellent tracking through laser guidance.
Employing MagnetoResistive (MR) Heads
The transition to Magneto Resistive (MR) heads have also been an important contribution to improved performance. MR heads can read data from a tape at faster speeds while allowing higher density of data on the tape itself. Combined, this can improve data transfer rates from 30-40%. For the future, MR heads will have to capacity to read high density tapes as SDLT and LTO tapes continue to improve data storage capability well into the muli-Tbytes range.
Connecting to SDLT and LTO to the SAN
Improved connectivity of SDLT and LTO are also an important factor in allowing them to integrate into a new generation of storage methods and technologies. Current SDLT drives employ Ultra SCSI for connectability, while LTO drives have both Ultra SCSI and Fibre Channel (FC) versions. When improvements in the drives and tape allow for fast data transfer rates, a bottle-neck at the connection is unacceptable. Upgrading the connection capability was critical for tape technologies was critical for current data rates and storage requirements.
While the concept of using tape for data storage may seem antiquated, tape cartridges still offer some distinct advantages - including great performance - that will make them part of an overall data storage strategy for some time to come. Improvements in elements of SDLT and LTO tapes and drives have solidified their place as demands on storage technology and performance continues to increase in the future.