Next Generation StorageTekTape Drive: T9840C

James CatesRobert Raymond

StorageTek Tape Drives - A CHOICE

Customers have a need for two different types of drives, which are ideally-suited for two different purposes:– “CAPACITY” drives for High Capacity

The StorageTek T9940 family of drives is designed and tuned for robust cost-effective capacity applications High performance, single reel cartridge design

– “ACCESS” drives for Fast Data RetrievalThe 9840 family of drives are designed and tuned for fast access, robust retrieval applications Maintains high performance dual reel cartridge design for all generationsT9840C third generation drive in the 9840 family

Tape Path and Cartridge Types

Dual HubInternal tape pathNo leader blocks

9840

Single HubExternal tape path

9840 Cartridge (no-covers)Idler

Tape GuidesTape Reels

Tape Path

Compliant Tape Guide(Stationary)Compliant

Tape Guide(Stationary)

9840 Cartridge – Tape Guide

CompliantSpring

Media

Fixed Flange(Reference Edge)

9840 Cartridge Demo

Video Provided by Imation Corporation

Data Access ComparisonData Access: Time from cartridge insertion in drive to first byte of data - timed to mid-point and does not include “robotic time”

Access SecondsT9840C 12

Capacity SecondsSingle hub 60-110cartridge drives

9840 Family SpecificationsParameters 9840A T9840B T9840C

Capacity (native) 20 GB 20GB19MB/sec

12 sec4 sec8 sec16 sec

2 Gbit/secDual port

70+ MB/sec8 m/sec

MP1

40GBData rate (native) 10MB/sec 30MB/sec

Access timeLoad

SearchRewind

12 sec4 sec8 sec16 sec

12 sec4 sec8 sec16 sec

FC speed 1 Gbit/secDual port

2 Gbit/secDual port

Compression speed 35MB/sec 70+ MB/secSearch velocity 8 m/sec 8 m/sec

Media MP1 MP1

T9840C Parameters

Parameter T9840C# of Parallel Channels 16Write Track Width (µm) 36Read Track Width (µm) 17

KFCI 163.6KBPI 162.0

Coding Efficiency 0.99Number of Tracks 288

Tape Velocity (m/sec) 3.3

9840 Tape Drive

Electronic

Module

CartridgeLoading

Assembly

9840 Electronic Module(4 Printed Wiring Board Assemblies)

System Processing

Card

Read/Write Card

Embedded Interface Card

Power DistributionCard

Block Diagram of Data StreamDigital

Processing

Write Driver

50-60 mAper channel

MediaTape Head

Pre-Amp

AGC & Filtering

Read Channel

Detection

1.0 – 2.0 mV

Read/Write Channel

Data Compression

Data Formating

User Data

Write Elements

MR Read Elements

Channel ElectronicsWrite driver must be capable of delivering write currents of the order of up to 60 mA0-pk per channel. Write current rise time required to be less than 5 nS.Analog pre-amps provide low noise amplification (50x to 100x) of the read signal from the head.Automatic gain control (AGC) is used to adjust for variations in signal amplitude and keep a fixed input signal to the read channel detection.Filtering is used to shape the waveforms for better detection.Read channel detection is dependent on the recording scheme.

T9840C PRML Channel

is a trademark of Overland Storage. technology is used to achieve T9840C capacity and performance.

Employs Overland Storage channel.Uses a EPR4 partial response target.Multiple diversity channels are used to address interchange, head wear and tape wear.One channel optimized for legacy read.

T9840C Servo Guiding

Servo employed to accurately control position of head relative to mediaMagnetic servo pattern pre-written on tapeServo readers located on magnetic recording headAmplitude based servo using a checkerboard pattern

Ferrofluid/MFM Images of 9840 Data Tracks and Amplitude Based Servo Tracks

6 servo tracks with bursts of servo signal. Servo head positions between tracks. 5 positions

54321

Direction of tape

Servo Patterns

5

4

3

2

1

T9840C Tape Head

Thin Film Write Head Cross-section

T9840C Head Design

T9840C Data Protection (ECC)

3 key designs protect customer data– Reed Solomon Encoding (RS)

Addition of bytes to customer bytes to enable recovery of customer bytes when some bytes are missing due to defects or damage to tape.

– Data Interleave and RotationThe distribution of Customer and RS bytes over a larger piece of the media, both down tape and across tape

– Sixteen Channel Recording Allow data to be distributed across the width of the tape

Reed Solomon Code• Customer data bytes are taken 36 at a time; an Error Correction System adds 12 unique bytes to the 36 to form a special group of 48

bytes. This group is called a codeword.

• A codeword, when read from media, has the following properties: if up to any 12 bytes are missing the remaining are used to re-create all 48 bytes - including the customers 36.

Customer Bytes ECC 48 byte CODEWORD

48 byte CODEWORD Customer Bytes ECC

Data Interleave and Rotation• The distribution of Customer and RS bytes over a larger piece of the

media, both down tape and across tape

Tape Motion

16 Tracks

ECC can recover if

up to 4 out of the 16

tracks have errors

Large Defects effect few bytes

Servo tracksCODEWORD

T9840 Family FeatureVolSafe ….for Compliance Copies – WORM (write once/read many) for Tape– Same capacity standard cartridge– Color cartridge markings to identify VolSafe– Special label identification– Drive identifies media as “Append Only”– SEC certified solution for archive

applications to US GovernmentAs an application in an existing library

All you need is the cartridge!

Questions?