[mythtv-users] [OT] Harddrive UDMA capabilities differ by IDE channel?

[William Munson]

Shaun Lowry wrote:
> I have 2 identical (or so I thought) Maxtor 250Gb drives in a software
> RAID0 configuration which I use for MythTV recordings etc.  Having
> just read an article on this list regarding hard drive performance
> (and having had some issues with this in the past) I decided to review
> my drive settings.  These 2 drives are connected to an el-cheapo PCI
> IDE add-in card on it's 2 primary channels.  When I run hdparm -i on
> these drives, I get different results for the UDMA modes!
>
> [root at medusa ~]# hdparm -i /dev/hde /dev/hdg
>
> /dev/hde:
>
>  Model=Maxtor 6B250R0, FwRev=BAH41BM0, SerialNo=B60VR1ZH
>  Config={ Fixed }
>  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57
>  BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=16
>  CurCHS=65535/1/63, CurSects=4128705, LBA=yes, LBAsects=268435455
>  IORDY=on/off, tPIO={min:120,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 *udma6
>  AdvancedPM=yes: disabled (255) WriteCache=enabled
>  Drive conforms to: (null):
>
>  * signifies the current active mode
>
>
> /dev/hdg:
>
>  Model=Maxtor 6B250R0, FwRev=BAH41BM0, SerialNo=B60GW0VH
>  Config={ Fixed }
>  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57
>  BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=16
>  CurCHS=65535/1/63, CurSects=4128705, LBA=yes, LBAsects=268435455
>  IORDY=on/off, tPIO={min:120,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=yes: disabled (255) WriteCache=enabled
>  Drive conforms to: (null):
>
>  * signifies the current active mode
>
> Could this be something odd to do with the controller card, or
> something up with one of the drives?
>   
Both drives use the same bios so they should have the same performance. 
Its possible that it is the controller however it is more likely that 
you have a standard and a highspeed ide cable. The standard cables have 
one wire per pin and the highspeed cables have an extra ground wire 
between each signal wire to reduce crosstalk. I think the standard 
cables have 40 wires and the highspeed have 80.