Testing High Performance Tape Drives

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• Testing High Performance Tape Drives

HEPiX FALL 2005 Data Services Section
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Motivation
LHC
2007
15 Petabytes/year
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Current Model
RFIO
DATA
DATA
DATA
DATA
CASTOR HSM
DATA
DATA
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Devices Tested
IBM 3592JA Tape Drive
IBM 3584 Library


Future Generation Tape Drives gt100 MB/s Testing
in 2006
300 GB / 60 GB
40 MB/sec
117 carts
12 drives
HP LT0-3
STK SL8500


400 GB
80 MB/sec
1,448 carts
64 drives
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Test Infrastructure
Tape Server
Tape Library
Fiber
Fiber Channel HBA
Tape Drive
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Functionality Tests

• Go through the set of commands available on the
  SCSI standard
• Check returned information, timing, command
  acceptance

SCSI COMMANDS Change Definition, Compare,
Copy, Copy and Verify, Display Message, Erase,
Format Medium, Inquiry, Load/Unload, Locate , Log
Select, Log Sense, Mode Select (6), Mode Select
(10), Mode Sense (6), Mode Sense (10), Persistent
Reserve In, Persistent Reserve Out, Prevent/Allow
Medium Removal, Read, Read Attribute, Read Block
Limits, Read Buffer, Read Position, Read Reverse,
Receive Diagnostic Results, Recover Buffered
Data, Release Unit (6), Release Unit (10), Report
Density Support LUNs, Request Sense Unit (6),
Reserve Unit (10), Rewind, Send Diagnostic, Set
Capacity, Space, Test Unit Ready, Verify, Write,
Write Attribute, Write Buffer, Write Filemarks
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Functionality Tests
fibre channel analyzer for verifying SCSI
commands
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Test Scenarios
Linux tape driver and cernTapeTestUtil
(interactive/command line mode)
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Analysis of Results
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Mechanical Tests
IBM 3592 Over 125,000 mount/dismount cycles
performed, no errors Test mechanical
reliability of drive / media some cartridges
now mounted gt 4000 times, no errors Random file
reads on selected tapes and media superseded
by CASTOR operation in data challenges HP
LTO-3 Over 125,000 mount/dismount cycles
performed, no errors Test mechanical reliability
of drive / media some cartridges now mounted gt
5000 times, no errors
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Performance Tests

• Use of native Linux Commands (mt/dd) for data
  transfers
• read / write
• compression / no compression
• blocksize
• filesize
• position labeled files

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Performance
LTO-3 Data Transfer Rate Write no compression
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Performance
LTO-3 Data Transfer Rate Read no compression
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Performance
LTO-3 Locate File Timing
Algorithm problem(?) seen older LTO-1 drives,
just HP (? )
LTO-3 Locate Record Timing
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ANSI Labels
Headers
Filename, block size, HSM version, time of
writing
Number of blocks, non standard data
Trailers
Tapemark
Special records on tape used by the drive ,
immediate bit 0/1
Sync
Flush buffer
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Labels vs Performance
Minimum over head
Maximum over head
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Labels vs Performance
HP-LTO3
IBM 3592JA
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Labels vs Performance
IBM 3592 small files
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HSM Integration

• Functionality Mechanical Performance

OK
Drive integration in HSM system

• tape_up tape unit standard testing for production
  utility
• tplabel tape labelling utility
• dumptape tape dumping (scanning) utility
• stagein tape reading utility
• stagewrt tape writing utility
• repack move CASTOR file from tape and reclaim
  utilities

Castor Production
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Operations
IBM 3592/HP LT0-3 SNMP Agent Error
Counters Tape Alerts Drive and Media number
mounts/Loads/ IBM 3592 Statistical Analysis
and Reporting System bit 62 SARS Drive
Relative Quality X'00' is unknown, best
X'01' -gt worst X'FF bit 63 SARS Media Relative
Quality X'00' is unknown, best X'01' -gt worst
X'FF' No Vendor Perfect tool for monitoring
all type of drives and for a large number of
drives
Request Sense
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More Tests
RFIO
CASTOR HSM

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