Disk performance

[Theodore J. Soldatos]

Theorhtiko thema ... :-)

Exo ta ekshs 2 mhxanhmata pou trexoun Linux 2.0.33:

1. (msfree) P166MMX, 64MB RAM me AHA-2940 UltraWide SCSI controller kai disko
Seagate Cheetah 4LP ST34501

2. (cthulhu) P200, 64MB RAM me 2 diskous - Quantum Fireball TM2550A kai Fireball
ST2.1A

Diavasa ena sygritiko test diskon, opou to throughput toy Cheeta evgaine gyro
sta 500 Kb/sec eno toy Fireball *SE* gyro sta 950 KB/sec. Den yphrxe anafora gia
to pos eginan ta test, oute kamia anafora an ta dyo megethi einai sygrisima
metaksy toys h me kapoia allh metrhsh (oi SCSI kai IDE diskoi htan ksexorista).
H entyposh omos pou pairno ego apo ayto einai oti o Cheetah exei thn mish
taxythta apo enan Fireball SE. Gia osous den ton kseroun, o Cheetah einai enas
panakrivos diskos, *theorhtika* poly kalos, me idiaitero xarakthristiko oti
gyrizei stis 10000 strofes kai thelei idiaiterh prosoxh sthn psyksh toy giati an
den psyxetai kala thganizeis aygo pano toy... 

Epeidh anamesa sta dyo parapano mhxanhmata exo dei terasties diafores stis
epidoseis yper toy Cheetah, anaroththika an ontos o SE einai toso poly kalyteros
apo ton ST oste na ksepernaei ton Cheetah (dedomenou kai toy UltraDMA). Opote
ekana merika tests me to hdparm (hdparm -t) kai me to bonnie
(http://www.tux.org/pub/benchmarks/Disk_IO/bonnie.tar.gz). Tha me endiefere an
kapoios exei Fireball SE na kanei ta idia test kai na mou steilei ta
apotelesmata. Thelo na matho ti apo ta dyo symbainei: Ego den ksero ti mou
ginetai, h aytos pou ekane to sygritiko ? Ta apotelesmata gia ton Cheetah kai
ton ST einai parakato (H epidrash toy cache einai apo elaxisth (bonnie) eos
mhdenikh (hdparm)): 

Bonnie: (diavaste to man toy gia leptomereies)

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
msfree    200  6276 93.0  9515 48.2  4031 37.0  6341 84.5 11004 39.4 102.7  4.4
<- O Cheetah ...
cthulhu   200  5618 87.2  5205 29.7  2456 26.4  5761 75.6  6511 31.8 44.7  1.8
<- Afora ton ST, oxi ton TM

hdparm:

------------- cthulhu -------------------
/dev/hda:

 Model=QUANTUM FIREBALL_TM2550A, FwRev=A6B.2400, SerialNo=39470546
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>5Mbs TrkOff }
 RawCHS=4969/16/63, TrkSize=32256, SectSize=512, ECCbytes=4
 BuffType=3(DualPortCache), BuffSize=76kB, MaxMultSect=16, MultSect=off
 DblWordIO=no, maxPIO=2(fast), DMA=yes, maxDMA=2(fast)
 CurCHS=4969/16/63, CurSects=5008752, LBA=yes, LBAsects=5008752
 tDMA={min:120,rec:120}, DMA modes: sword0 sword1 sword2 mword0 mword1 *mword2 
 IORDY=on/off, tPIO={min:300,w/IORDY:120}, PIO modes: mode3 mode4 

 Timing buffered disk reads:  32 MB in  5.74 seconds = 5.57 MB/sec

/dev/hdb:

 Model=QUANTUM FIREBALL ST2.1A, FwRev=A0F.0800, SerialNo=15571636
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
 RawCHS=4092/16/63, TrkSize=32256, SectSize=512, ECCbytes=4
 BuffType=3(DualPortCache), BuffSize=81kB, MaxMultSect=16, MultSect=off
 DblWordIO=no, maxPIO=2(fast), DMA=yes, maxDMA=2(fast)
 CurCHS=4092/16/63, CurSects=4124736, LBA=yes, LBAsects=4124736
 tDMA={min:120,rec:120}, DMA modes: sword0 sword1 sword2 mword0 mword1 *mword2 
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, PIO modes: mode3 mode4 

 Timing buffered disk reads:  32 MB in  3.75 seconds = 8.53 MB/sec

------------ msfree -----------

/dev/sda:
 Timing buffered disk reads:  16 MB in  0.41 seconds =39.02 MB/sec
                                                      ^^^^^^^^^^^^
						*Poly* megalh diafora... 

T.

-- 
Theodore=J.=Soldatos=_\_="There=is=always=a=bug=somewhere",=said==HAL=to=the==
=  theodore at eexi.gr =_/_==Ultimate=Programmer,=and=turned=off=the=air=supply.=
=====================_\_="Everybody=knows=the=war=is=over,====================
==== Scientific =====_/_==everybody=knows=the=good=guys=lost"===Leonard=Cohen=
= Publications Ltd. =_\_============ http://w4u.eexi.gr/~theodore ============
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