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The 3490-A02 is an 18-track, 2 Control Unit component for an IBM 3490
tape subsystem. The IBM 3490 Model A02 supports the 3490 Model B02 and
B04 18-track Tape Drive Units. The subsystem will occupy approximately
50 percent less floor space than a comparable 3480 configuration by incorporating
up to two control unit functions in one box. The Model A02 can be field
upgraded to a Model A20, providing granularity from a minimum 2x2 (A02
x B02-18 track) configuration to a maximum 2x16 (A20 x four B40-36 track)
configuration. Included as standard in the Model A02 is Improved Data
Recording Capability (IDRC), dual communications capability, and a 2 Mb
buffer. Components in the control units are serviced from the rear to
minimize operational interference.
The 3490 Model A02 contains two 18-track control unit functions and one
power supply in each control unit. Their design and standard features
combine to provide significant environmental savings, enhanced performance,
and operational efficiency. The enhanced packaging can provide up to 50
percent floorspace savings when compared to similar 3480 configurations.
The smaller floorspace reduces operator travel time and contributes to
improved operational efficiency. Components in the control units are serviced
from the rear to minimize operational interference.
The Model A02 will attach up to four Model B04 drive units or up to four
Model B02 drive units. Model B02 and B04 drive units can be mixed in the
same configuration up to a maximum of 4 drive units per Model A02. In
mixed configurations the Model B02 must be placed following all Model
B04 drive units. Up to four channel attachments can be specified per control
unit function for a total of eight channel attachments per A02. All channel
adapters and drives are treated as a collective resource available to
both control unit functions. The 3490 supports 1.5, 2.0, 3.0, and 4.5
Mb/Sec channel data rates. The cable distance of the 3490 A02 can be extended
using the IBM 3044 Fiber-Optic Channel Extender Link Model C02 and D02
with the Enhanced Tape Attachment Feature (#6053), see ESCON Adapter section
for details.
Improved Data Recording Capability (IDRC), which is standard, can increase
effective cartridge capacity by up to five times and in conjunction with
4.5 Mb/Sec. channels, can improve subsystem performance by up to 70 percent
when compared to 3480 attached to 3.0 Mb/Sec channels. The 3490 A02 can
read and write 3480 recording format providing complete data interchange
with the 3480.
Business Solutions
The 3490 A02 subsystem requires up to 50 percent less space than is required
for an equivalent number of 3480 tape drives.
The IBM 3490 Model A02 contains two logical control units, each with
a 2Mb dynamic buffer, attaches up to 16 drives and up to eight channel
attachment features.
The IBM 3490 requires no scheduled preventive maintenance. IBM customer
engineers use a microprocessor-based maintenance device to perform diagnostics
and repairs. Service is accomplished from the rear of the Model A02, improving
user operations and drive availability.
User Productivity
IBM technology, featuring thin film heads, improved error correction
capability, and enclosed tape cartridges, offers high availability. This
technology is included in all IBM 3490 product family members. The proven
IBM error correction capability has been implemented through error recovery
programs in the control unit's microcode.
The Improved Data Recording Capability (IDRC) is standard on Model A02.
When utilizing IDRC, fewer cartridges may be required to store the same
amount of data, resulting in fewer mounts and demounts, shorter rewind
times, and fewer cleaning cycles. IDRC also provides up to 70 percent
tape performance improvement compared to 3480 tape drives operating with
3Mb/sec channels without the IDRC feature.
The 2Mb buffer in the control unit allows data to be transferred between
the buffer and the channel at channel data transfer rates, since the host
processor doesn't have to wait for the physical drive to respond to read
and write commands.
During read operations, the buffer permits the control unit to respond
rapidly to host read commands by prereading multiple data records from
drives into the buffer. Similarly, during write mode operations, multiple
data records can be transferred from a host to a control unit's buffer
at channel speeds.
Growth Enablement
The 3490 Model A02 is upgradeable to the Model A20. The Model A20 supports
the 36 track drive units Models B20 and B40.
The 3490 Models A02 may be attached to any of the following hosts processors.
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