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

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testing high performance tape drives
Testing High Performance Tape Drives

HEPiX FALL 2005

Data Services Section

motivation

Motivation

LHC

2007

~15 Petabytes/year

slide3
Current Model

RFIO

DATA

DATA

DATA

DATA

CASTOR

HSM

DATA

DATA

slide4
Devices Tested

IBM 3592JA Tape Drive

IBM 3584 Library

+

+

Future Generation Tape Drives >100 MB/s

Testing in 2006

300 GB / 60 GB

40 MB/sec

117 carts

12 drives

STK SL8500

HP LT0-3

+

+

400 GB

1,448 carts

80 MB/sec

64 drives

test infrastructure
Tape Server

Tape Library

Test Infrastructure

Fiber

Fiber Channel HBA

Tape Drive

functionality tests

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

mechanical tests

Mechanical Tests

IBM 3592:

Over 125,000 mount/dismount cycles performed, no errors

Test mechanical reliability of drive / media: some cartridges now mounted > 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Random file reads on selected tapes and media: superseded by CASTOR operation in data challenges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 > 5000 times, no errors

performance tests

Performance Tests

  • Use of native Linux Commands (mt/dd) for data transfers :
    • read / write
    • compression / no compression
    • blocksize
    • filesize
    • position “labeled” files
performance14
LTO-3 Locate File Timing

Algorithm problem(?) seen older

LTO-1 drives, just HP (? )

LTO-3 Locate Record Timing

Performance

slide15
80 Bytes

0-? Bytes

80 Bytes

80 Bytes

80 Bytes

80 Bytes

80 Bytes

Trailer 2

Trailer 1

Header 3

Trailer 3

Header 1

Data

Header 2

Tapemark

Tapemark

Tapemark

Sync

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

slide16
Labels vs Performance

Minimum

over head

Maximum

over head

slide17
Labels vs Performance

HP-LTO3

IBM 3592JA

slide18
Labels vs Performance

IBM 3592

small files

hsm integration

HSM Integration

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

Functionality + Mechanical + Performance

Castor Production

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' -> worst X'FF‘

bit 63 SARS Media Relative Quality

X'00' is unknown, best X'01' -> worst X'FF'

No Vendor:

Perfect tool for monitoring all type of drives and for a large number of drives

Operations

Request Sense

slide21
SAN

More Tests

RFIO

CASTOR

HSM

$$

??

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