Data Compression - Compaq StorageWorks SDLT 110 Reference Manual

Table 1–1 shows the categories of controllers that support the SDLT drive and which
ones are recommended.
Table 1–1: Supported Controllers
Controller Categories
Fast SCSI-2 (Narrow)
Fast SCSI-2 (Wide)
Wide-Ultra SCSI
Ultra-2 SCSI
Ultra-3 SCSI
NOTE: Equipping the server with at least a Wide-Ultra SCSI Controller is recommended.
For a list of specific controllers and adapters that support the SDLT drive refer to:
www.compaq.com

Data Compression

The SDLT drive reads and writes both uncompressed (native) and compressed data.
• The SDLT 110/220 drive features a native formatted capacity of 110 GB and a
sustained native data transfer rate of 11 MB/s.
• The SDLT 160/320 drive features a native formatted capacity of 160 GB and a
sustained native transfer rate of 16 MB/s.
When operating in compressed mode, data capacity is affected by how much the data
can be compressed. Most data can be compressed at an approximate 2:1 ratio. This
would provide the SDLT 110/220 drive with a compressed capacity of 220 GB and a
compressed data transfer rate of 22 MB/s. The SDLT 160/320 has a compressed
capacity of 320 GB and a compressed data transfer rate of 32 MB/s.
The SDLT drive ships from the factory with data compression enabled for writing. In
this mode, data is always compressed when writing to the tape, but the drive is capable
of reading both compressed and native tapes. For the drive to write native data, the
data compression setting must be changed through the software. To change the setting,
consult the backup application software documentation for the data compression
enabling and disabling procedure.
IMPORTANT: Capacity may vary based upon actual stored data. Data transfer rates can vary
depending on actual data, media condition, and system and controller capabilities.
StorageWorks SDLT Tape Drive by Compaq Reference Guide
Introducing the SDLT Drive
Recommended
No
No
Yes
Yes
Yes
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