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Subjectiozone lies/bug ?
Hi all...

This is a curious thing, I think...
I wanted to test the speed of an usb stick, and as a first step used hdparm
on my root disk (real SCSI) and on the stick:

werewolf:/media/media# lsscsi
[1:0:0:0] disk SEAGATE ST336807LW 0C01 /dev/sda
[1:0:1:0] disk SEAGATE ST336807LW 0C01 /dev/sdb
[2:0:0:0] disk ATA ST3120022A 3.06 /dev/sdc
[2:0:1:0] cd/dvd HL-DT-ST DVDRAM GSA-H10N JL12 /dev/sr0
[4:0:0:0] disk ATA ST3200822AS 3.01 /dev/sdd
[5:0:0:0] disk ATA WDC WD3200AVJS-6 12.0 /dev/sde
[7:0:0:0] disk USB DISK 2.0 1219 /dev/sdf
werewolf:/media/media# hdparm -tT /dev/sda /dev/sdf

/dev/sda:
Timing cached reads: 1402 MB in 2.00 seconds = 700.54 MB/sec
Timing buffered disk reads: 226 MB in 3.02 seconds = 74.86 MB/sec

/dev/sdf:
Timing cached reads: 1272 MB in 2.00 seconds = 635.69 MB/sec
Timing buffered disk reads: 52 MB in 3.02 seconds = 17.20 MB/sec

Well, looks reasonable.
But, as hdparm is not a 'serious' test, and I wanted also write speed,
used iozone:

werewolf:/media/media# iozone -v
'Iozone' Filesystem Benchmark Program

Version $Revision: 3.287 $
Compiled for 32 bit mode.

But it gives strange results:

for sda1 (/):

Machine = Linux werewolf.home 2.6.26-jam07 #1 SMP PREEMPT Mon Sep 1 01:47:23 C Auto Mode
Auto Mode
File size set to 4096 KB
Command line used: iozone -M -a -s 4m
Output is in Kbytes/sec
Time Resolution = 0.000001 seconds.
Processor cache size set to 1024 Kbytes.
Processor cache line size set to 32 bytes.
File stride size set to 17 * record size.
random random bkwd record stride
KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
4096 4 180855 742576 1275252 1130840 1143176 597607 998780 670266 1168616 231962 670815 1071129 1259145
4096 8 247673 809183 1246875 1407083 1351815 711728 1176673 854936 1298668 236817 744321 1233363 1519851
4096 16 251644 851010 1123131 1691931 1668431 716459 1094017 931544 1259145 245622 793337 1110328 1659643
4096 32 253245 871663 1463432 1764719 1808388 757396 1339875 885813 1393197 261107 796112 1128374 1742978
4096 64 254837 862332 1139037 1789405 1585752 779448 1136199 961728 1844214 259684 799687 1124965 1538114
4096 128 250090 868154 1177029 1715966 1700996 771810 1181084 980842 1643659 228405 792569 1003429 1720285
4096 256 242984 791959 950372 718080 930274 826472 694472 708038 913470 223751 566606 698737 918385
4096 512 238696 664406 764459 803304 720492 519335 727660 420102 686557 212735 416768 728695 695534
4096 1024 232926 667198 711975 773266 735896 689562 781828 663857 742297 253183 541297 658732 816912
4096 2048 243548 659167 653899 738807 728048 632684 638304 493137 599707 305011 660858 664180 792569
4096 4096 218417 655142 857449 732729 694826 696717 689098 557278 627643 242913 610705 713588 784073

for sdf1:

Machine = Linux werewolf.home 2.6.26-jam07 #1 SMP PREEMPT Mon Sep 1 01:47:23 C Auto Mode
Auto Mode
File size set to 4096 KB
Command line used: iozone -M -a -s 4m
Output is in Kbytes/sec
Time Resolution = 0.000001 seconds.
Processor cache size set to 1024 Kbytes.
Processor cache line size set to 32 bytes.
File stride size set to 17 * record size.
random random bkwd record stride
KB reclen write rewrite read reread read write read rewrite read fwrite frewrite fread freread
4096 4 391850 843302 885058 1159992 746900 704385 778707 566371 941825 481712 772247 1204705 795494
4096 8 385690 981087 1036709 1419270 945740 755162 978967 555842 1211475 390392 919622 1209329 1071970
4096 16 613438 1121897 1335497 1594434 1441745 683008 1217598 973152 1117903 558038 1014363 1144453 1552103
4096 32 559635 968335 1494912 1601847 1676627 1129619 1491081 1264978 1675941 604932 1051334 1217598 1629276
4096 64 627925 1197687 1557477 1697406 1573569 1082738 1589445 1237462 1755679 587830 1090812 1216513 1678000
4096 128 538446 1177653 1366266 1268879 963537 796422 981548 983197 1582077 428272 977099 1431167 1643000
4096 256 611078 1160652 907177 1041725 1114861 1214349 1088204 1161985 813343 454051 552021 919003 984852
4096 512 448633 912842 725981 782419 722526 983197 579103 870748 644937 432341 632684 718092 768336
4096 1024 473859 816750 717209 795504 738683 660964 694472 793337 716083 385070 699573 718092 760207
4096 2048 513161 789051 685059 768041 718974 652437 643418 639500 715583 486749 881049 715708 747854
4096 4096 505174 700760 835748 775173 786029 794414 797507 718470 594830 408904 835066 637608 670815

First, Output is not in Kb, or I have a disk that gives 1Gb/s... :).
And second, how can both drives give the same ? The file is too small ?
Do I need -e to iozone to account for sync ? But that would not affect read
speed...
Strange (for my understanding).

TIA

--
J.A. Magallon <jamagallon()ono!com> \ Software is like sex:
\ It's better when it's free
Mandriva Linux release 2009.0 (Cooker) for i586
Linux 2.6.25-jam18 (gcc 4.3.1 20080626 (GCC) #1 SMP


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