Compaq Tandem 5145 4mm DAT (DDS3)

The 5145 Digital Audio Tape (DAT) delivers the economies of DAT technology in a cartridge tape drive specially designed and packaged for use in Compaq NonStop™ Himalaya servers.

The exceptionally high capacity of the 5145 DAT, its low cost per megabyte, and its read/write speed make it an excellent choice for tape backup for entry-level Compaq NonStop™ Himalaya servers. Employing the newest Data-Phone Digital Service (DDS) DDS-3 recording techniques with onboard hardware data compression, the 5145 DAT can store as many as 24 gigabytes of data on a single cartridge and read or write up to 2 megabytes of data per second. The DAT standards committee has set the DDS-3 data recording format to be backward read/write compatible with the previous DDS and DDS-2 recording formats. Thus, a 5145 DDS-3 machine can process the tape media created on the previous 5141 DDS-2 systems. This feature enables the 5145 DAT to be added to an operations environment that includes 5141 DAT subsystems. Note, however, that the 5141 DDS-2 subsystems cannot process media created in the DDS-3 recording format.

Figure 1. 5145ACL desktop subsystem with six-cartridge automatic cartridge loader.

The 5145 DAT is easy to operate. It features a 32-character, interactive control panel and an internal self-test diagnostic routine that lets you quickly ascertain the status of the drive. The 5145 DAT also includes flash EPROM memory that lets you easily update microcode or performance options.

The 5145 DAT drive can be installed while your Compaq NonStop™ Himalaya servers remain online, and it requires no application rewrites or additional software. With its superior operational characteristics and low cost, it is well suited for the Compaq NonStop™ Himalaya environment, where performance and reliability are critical.

High-capacity cartridge tape storage

The 5145 drive is a third-generation DAT drive that employs DDS, DDS-2, and DDS-3 high-density recording techniques to provide maximum storage capacity per cartridge tape.

Using the new DDS-3 recording method, the 5145 DAT media can store as many as 12 gigabytes of uncompressed data or 24 gigabytes of compressed data on a single cassette. (Each 5145 DDS-3 cartridge contains 125 meters of 4-millimeter tape.)

Because it can store such a large amount of data on a small amount of tape, the 5145 DAT is able to back up the database of a typical entry-level Compaq NonStop™ Himalaya server on only one or two cassettes, drastically reducing the amount of operator involvement in tape backup procedures.

With the 5145 DAT, operators change tape cartridges far less frequently than with older cartridge or open-reel tape media. The amount of data stored on a single 5145 DAT cartridge (12 gigabytes) would occupy 94 Compaq NonStop™ Himalaya 5126 tape drive cartridges or 80 standard 2,400-foot reels of 0.5-inch, 9-track tape encoded at 6,250 bits per inch. With typical 2:1 data compression, a single DDS-3 data cartridge can store 24 gigabytes, or the equivalent of 160 half-inch, 9-track, 2,400-foot open reel tapes or 188 Compaq NonStop™ Himalaya 5126 cartridges.

The 5145ACL offers the added functionality of a six-cartridge automatic cartridge loader (ACL). Thus, up to 144 gigabytes of data can be written to tape with a single insertion of a six-cartridge data magazine. Operator intervention can be practically eliminated for most entry-level Compaq NonStop™ Himalaya servers.

Low cost per megabyte

The 5145 DAT offers the best price/performance of any tape subsystem designed for use with Compaq NonStop™ Himalaya servers. In many cases, only a single cartridge is required for the backup of an entire database (up to 24 gigabytes), so operations can schedule unattended nightly system backups. Significant savings can be achieved in the cost of equipment and operator time.

In addition, the low price of the 5145 DAT makes it feasible to run multiple 5145 DAT drives in parallel at a single site for increased performance or storage capacity.

The price per megabyte of the 5145 DAT is about US$0.0050 per megabyte for uncompressed data and $0.0025 for compressed data. In comparison, the price per megabyte of the Compaq NonStop™ Himalaya 5126 tape cartridge drive is about $0.32 per megabyte.

High performance*

The read/write performance of the 5145 DAT lets you complete backup operations in less time than with other comparable media.

The maximum burst data-transfer rate of the 5145 DAT, without using data compression, is 1,000 kilobytes per second, for a total of 3.6 gigabytes per hour. The effective burst data-transfer rate using data compression is 2 megabytes per second. (To achieve sustained data-transfer rates exceeding 400 kilobytes per second, the 5145 DAT must be connected to a Compaq NonStop™ Himalaya 3214 dedicated tape controller. However, the maximum data-transfer rate is limited by the 3214 controller’s bandwidth, which is about 50 percent of the device’s effective data-transfer rate).

Using the uncompressed rates above, backing up 12 gigabytes of data with the 5145 DAT can save up to approximately 22 hours compared with the Compaq NonStop™ Himalaya 5126 drive.

Manageability features
The 5145 DAT drive incorporates several features that help operators monitor and control backup operations. Among these are the following:

• 32-character, interactive control panel. The LCD control panel of the 5145 DAT can display a variety of information for operators, including current operation, performance data, compression status, error codes, and a message indicating that routine maintenance is necessary. Using the control panel in conjunction with the mode button, operators can enable or disable data compression and initiate internal self-test diagnostics.
• Internal self-test diagnostic routines. These routines enable the 5145 DAT to diagnose problems with its drive or electronics while off-line. Error codes are displayed on the control panel.

Rapid installation

Installing a 5145 DAT drive is as simple as connecting a SCSI cable. The 5145 DAT emulates the protocols of the Compaq NonStop™ Himalaya 517x tape subsystem, so no application rewrites or additional software is necessary.

Using Compaq NonStop™ Himalaya’s standard SCSI cables, the 5145 DAT connects to either a Compaq NonStop™ Himalaya multifunction controller (MFC) or a Compaq NonStop™ Himalaya 3214 dedicated tape controller. A variety of cable lengths is available.

Figure 2. 5145 single loading desktop subsystem.

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