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LTO vs SDLT

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LTO versus SDLT

Two competing tape technologies dominate the enterprise backup segment, LTO and SDLT. The current top 2 drive technologies are LTO3 and SDLT600 respectively. Both products represent evolution from a previous generation rather than complete new products. This is preferable as it ensures compatibility with a large range of existing tape libraries and provides backward read compatibility with the previous generation of product. Both factors offer continued protection of investment.

The LT03 significantly raises the bar, both in capacity per tape and with significantly higher drive transfer rates. To obtain the maximum performance from these new drives it will be important to use a back-up server equipped with the appropriate newer generation of high speed interface cards (see SCSI Information). Typically these servers will utilise PCI-X interface technology which provides internal bus speeds capable of supporting these data rates. [Functional Software has conducted testing with these higher performance drives and can ensure you get the most from your implementation of LT03 based libraries.]

DLT tape has been the other tape standard for enterprise use for many years. There are thousands of companies around the world that rely on this well proven technology to protect their data. The SDLT600 is read compatible with the SDLT320 but utilises a new cartridge, Super DLTtape II, to obtain its 300Gbyte native (600Gbyte compressed) capacity. The previous generation product, the SDLT 320, used the same Super DLTtape I cartridges as the SDLT 220 and is backward read compatible with DLTtape IV media, preserving investments in previous DLT technologies. For this reason alone DLT will continue to be a player in the tape market.

In the comparison table below the HP Ultrium LTO2 product specs have been used. The HP drive incorporates Adaptive Tape Speed which dynamically matches the transfer rates of slower hosts (from 10 MB/s upwards), which increases performance, reduces mechanical wear on the drive and extends tape life.


Comparison Chart


* AMP : Advanced Metal Particle ** MP : Metal Particle ***AME : Advanced Metal Evaporated Note:
LTO3
HP Ultrium 960
SDLT600
Quantum
LTO2
HP Ultrium 460
SDLT320
Quantum
Native Capacity (GB) 400 300 200 160
Compressed Capacity (GB) 800 600 400 320
Media Type MP** AMP* MP** AMP*
Drive LT03 Ultrium SDLT600 LT02 Ultrium SDLT320
Drive Transfer Rate (Native) (MB/s) 80 36 30 16
Drive Transfer Rate (Native) (GB/h) 288 133 108 57
Drive Transfer Rate (Comp.) (MB/s) 160 72 60 32
Interfaces Available LVD ULTRA, 320 SCSI,
2 GB Fibre Channel
LVD ULTRA, 160 SCSI,
2 GB Fibre Channel
LVD Ultra-3 SCSI,
2 GB Fibre Channel
Ultra 2 LVD and
HVD SCSI
Cartridge Memory LTO-CM No LTO-CM No
Compression Technology ALDC ( 2 : 1 ) DLZ (2 : 1) ALDC ( 2 : 1 ) DLZ (2 : 1)
MTBF - hours 250,000 250,000 250,000 250,000
Form Factor 5.25inches 5.25inches 5.25inches 5.25inches
Backward Read Compatible? Read and Write compatible with LTO2, Read compatible with LT01 Read and Write compatibility with SDLT320. See Notes below Read and Write compatible with LTO1 1st generation. Read compatibility with dual-head design - see note
Backward Write Compatible? Read and write compatible with LTO2 No Read and write compatible with LTO1 No