hugo caçote @ hepix fall 2005 testing high performance tape drives hepix fall 2005 data services...

Hugo Caçote @ HEPiX Fall 2005

Testing High Performance Tape Drives

HEPiX FALL 2005Data Services Section


Motivation

2007

~15 Petabytes/year

LHC


Current Model

CASTORHSM

RFIOD

ATA

DA

TA

DA

TA

DA

TA

DA

TA

DA

TA


IBM 3584 Library IBM 3592JA Tape Drive

HP LT0-3STK SL8500

400 GB

80 MB/sec

40 MB/sec 300 GB / 60 GB

1,448 carts 64 drives

117 carts12 drives

+ +

+ +

Devices Tested

Future Generation Tape Drives >100 MB/s

Testing in 2006


Test Infrastructure

Tape Library

Tape Drive

Fiber

Fiber Channel HBA

Tape Server


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


Functionality Tests

fibre channel analyzer for verifying SCSI commands


Test Scenarios

Linux tape driver and cernTapeTestUtil (interactive/command line mode)


Analysis of Results


Mechanical Tests

IBM 3592:Over 125,000 mount/dismount cycles performed, no

errorsTest mechanical reliability of drive / media: some

cartridges now mounted > 4000 times, no errorsRandom 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superseded by CASTOR operation in data challenges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

- Use of native Linux Commands (mt/dd) for data transfers :

• read / write• compression / no compression• blocksize• filesize• position “labeled” files


Performance

MBytes/s with blocksize, L30099

01020304050607080

Blocks (K)

MB

ytes

/sLTO-3 Data Transfer RateLTO-3 Data Transfer Rate

Write no compressionWrite no compression


Performance

LTO-3 Data Transfer RateLTO-3 Data Transfer RateRead no compressionRead no compression

MBytes/s with blocksize, L30100

01020304050607080

Blocks (K)

MB

ytes

/s


Skipping 40 MB files

0

20

40

60

80

100

120

140

160

180

1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271

Groups of 33 labelled files

Se

co

nd

s

Skip

Rewind

LTO-3 Locate File Timing

Skipping 512 MB steps

0

20

40

60

80

100

120

140

1 37 73 109 145 181 217 253 289 325 361 397 433 469 505 541 577 613 649 685 721 757

Skips

Se

co

nd

s

Skip

Rewind

LTO-3 Locate Record Timing

Performance

Algorithm pro

blem(?) se

en older

LTO-1 drives,

just HP (?

)


Tapemark

Data

0-? Bytes

Tapemark

Header 1

80 Bytes

Header 2

80 Bytes

Header 3

80 Bytes

Trailer 1

80 Bytes

Trailer 2

80 Bytes

Trailer 3

80 Bytes

Tapemark

Sync

ANSI Labels

Headers

Trailers

Tapemark

Sync

Filename, block size, HSM version, time of writing …

Number of blocks, non standard data …

Flush buffer

Special records on tape used by the drive , immediate bit =0/1


Average Effective Write Data Transfer HP LTO-3

0

10

20

30

40

50

60

70

0 500 1000 1500 2000

File Size/MBytes

Dat

a Tr

ansf

er M

Byt

es/s Imm=1Tpmrk=3 Sync=1

Imm=0 Tpmrk=3 Sync=1




Labels vs Performance

Minimumover head

Maximumover head


Average Effective Write Data Transfer HP LTO-3 vs IBM 3592JA

0

10

20

30

40

50

60

70

0 200 400 600 800 1000 1200 1400 1600 1800 2000

File Size/MBytes

Dat

a Tr

ansf

er M

Byt

es/s

Imm=1Tpmrk=3 Sync=1 LTO3

Imm=0 Tpmrk=3 Sync=1 LTO3




Imm=1Tprmk=3 Sync=1 3592

Imm=0 Tpmrk=3 Sync=1 3592





HP-LTO3

IBM 3592JA


Average Effective Write Data Transfer HP LTO-3 vs IBM 3592JA

0

10

20

30

40

50

60

70

0.25

1 4 7

10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97

100

400

700

1000

2024

File Size/MBytes

Dat

a T

ran

sfer

MB

ytes

/s

Imm=1Tpmrk=3 Sync=1 LTO3











IBM 3592small files


HSM Integration

Functionality + Mechanical + Performance

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

OK

Drive integration in HSM system


Operations

IBM 3592/HP LT0-3:SNMP Agent :

Error CountersTape AlertsDrive 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

Request Sense


More Tests

CASTORHSM

RFIO

?? $$SAN

hugo caçote @ hepix fall 2005 testing high performance tape drives hepix fall 2005 data services...

Documents

hugo caote

compression slide

filemarks slide

petabytesyear lhc slide

performance lto

bytes trailer

data transfers

buffered data