Re: Change UDMA level in running system (was Re: disk problems or false alarm??)

[Alexander Dalloz]

Am Sa, den 01.05.2004 schrieb bit um 19:59:

>  Using "hdparm -i /dev/hdX", I found out, that both of my
> hard drives run in 
>  udma2, while they are capable of udma5.
>  
>   PIO modes:  pio0 pio1 pio2 pio3 pio4 
>   DMA modes:  mdma0 mdma1 mdma2 
>   UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5 
>   AdvancedPM=yes: disabled (255) WriteCache=enabled
>   Drive conforms to: ATA/ATAPI-5 T13 1321D revision 1: 
>  
>  I didn't investigat this any further, apart from reading the hdparm man pages, 
>  but is it advisable to change from udma2 to udma5 in a completely installed 
>  and configured OS generally (or FC1 in special) ? 
Normally the kernel automatically sets the proper transfer rate and mode
automagically. There are just few cases where it makes sense to override
that manually.

I does not only matter for which transaction mode your hard drive is
capable but also which modes the IDE bus controller chip supports. Given
that your motherboard/IDE controller supports UDMA5 too like your hard
drive, then you can change the mode with:0)100MB/sec

hdparm -X69 /dev/hdX

But if your motherboard only supports ATA33 (UDMA2) or you have just a
40pin IDE ribbon cable the change will not happen or change anything.

>  Sorry for hijacking the thread, but I felt it was kinda
> "apropriate". :-) 
No, it is no hijacking, your question just focuses on a specific part of
the original thread. Don't worry ;)

>  Thanks for any help.
>  
>  > Alexander
>  
>  Have phun,
>  bit 
Alexander


-- 
Alexander Dalloz | Enger, Germany | GPG key 1024D/ED695653 1999-07-13
Fedora GNU/Linux Core 1 (Yarrow) on Athlon CPU kernel 2.4.22-1.2188.nptl
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