IBM System Storage TS3500, Введение и руководство по планированию

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TS1130, and TS1140 tape drives), and JY Advanced WORM cartridge (for
TS1140 tape drives). WORM cartridges are factory-formatted as WORM
cartridges and may not be converted to data cartridges. The 3592 tape
drives allow append operations to data already on WORM cartridges, but
do not allow data to be overwritten under any circumstances.
Capacity-based and position-based LEOT reporting
The TS1120 and later tape drives use enhanced logic to report logical
end-of-tape (LEOT) data. The drive reports LEOT based on a combination
of indicators of capacity-based LEOT and position-based LEOT. These
drives monitor the total accumulated physical tape files written to the
cartridge and report the LEOT based on the capacity-based LEOT value,
rather than reporting LEOT based on the physical position on the tape
(position-based LEOT). To summarize, this technique reports LEOT based
on the amount of compressed data that is recorded to the cartridge and
reduces the variation in the amount of data recorded before LEOT is
issued. For applications that use LEOT to stop the write process, a more
consistent capacity is recorded to the media. For a higher percentage of the
time, this process allows tape copies to complete without overflow.
Enhanced format for recording error-correction codes (ECCs)
The logical formats of TS1120 and later tape drives offer improved
error-correction-code capabilities over the 3592 J1A and LTO formats by
increasing the power of one of the two orthogonal Reed-Solomon ECCs
that protect the data on tape. The correction power of the inner code is
approximately double that of the 3592 J1A and thus offers superior
reliability of the data.
Drive mechanical and electrical reliability
The mechanism of the TS1120 and later tape drives is specified at a
mean-cycles-between-failure rate of 300,000 cycles, which is the highest
reliability rating in the industry. The mechanism contains special
mechanical and electrical features to prevent damage to the media on
power-down or reset. These features also prevent the dropping of the
leader pin or other thread failures during similar interruptions. It also
tolerates extremely high vibration and shock environments without data
loss or degraded operation.
Multiple subsystem and automation support
The 3592 tape drives and their cartridges support multiple automation
libraries and can be easily transported between environments.
Data compression
The 3592 tape drives use the data-compression method known as
streaming lossless data compression algorithm. The compression logic for
TS1120 and later tape drives operates at more than twice the overall
transfer rates of the 3592 J1A tape drive.
Data buffer with read ahead feature
The 3592 J1A tape drive includes a data buffer of 134.22 MB (128 MiB). The
TS1120 tape drive includes a data buffer of 536.87 MB (512 MiB). The
TS1130 tape drive and TS1140 tape drive each include a data buffer of 1.07
GB (1 GiB). Along with enabling performance characteristics in buffered
Write and Read commands, the data buffer also supports a Read Ahead
feature. When the drive processes a command to locate or read a block, the
drive automatically continues to stream down the tape and read ahead
until the data buffer is full. This allows subsequent Locate or Read
commands to be fulfilled from the data buffer at faster speeds, rather than
requiring access to the tape.
Chapter 1. Introduction
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