same disk model butt different ....

[K.C. Chan]

All,
I have two ide disks of the same model on two server with the same hardware. How come the udma option is different between the two. Below is an informational output from hdparm:

on system1:
/dev/hda:

Model=ST340016A, FwRev=3.75, SerialNo=3HS6E510
Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=16
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=78165360
IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: device does not report version: 1 2 3 4 5


on System2:
/dev/hda:

Model=ST340016A, FwRev=3.75, SerialNo=3HS6FHB0
Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=16
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=78165360
IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 *udma2
AdvancedPM=no WriteCache=enabled
Drive conforms to: device does not report version: 1 2 3 4 5

any idea why system1 is capable of udma5 and system2 is not? The reason I am asking about this is because system1 seems to have better I/O throughput compare to system2.

[Steven E. Protter]

I have to say that is really strange. The firmware is the same, the drives should be the same.

Two ideas come to mind:

1) The manufacturer added a feature that is not controlled by firmware.
2) The drive was modified by bios/OS to do UDMA5.

Suggestion: Bring this question to the drive manufacturer. They should explain it.

Suggestion2: Monitor i/o performance with the sar tools and see if your perception of an i/o advantage is in fact a reality.

SEP

[Dave Falloon]

Everything is the same, ie. kernel, jumpers, motherboard, cables, bios settings, hdparm versions?

My gut is telling me something is different, first thing that pops into my head is cabling/jumper configuration.

If they are indeed identical then I would call Seagate, like SEP suggested.

--Dave

[Vitaly Karasik_1]

You may put hardrive from the first box to the second one - probably it'll help to understand what is different.