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?
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