DMA RAID query

[Phillip Susi]

It isn't that simply having the drives there slow things down, it is 
using them.  IDE can only talk to one of the two drives at a time, so if 
you are reading data from the cdrom, or burning a disc in the writer, 
then the hard drive throughput will drop like a rock. 

dave s wrote:
> Hi all,
>
> I have a working RAID 1 setup
>
> hda HDD 180GB RAID
> hdb DVD burner/reader
> hdc HDD 180GB RAID
> hdd DVD reader
>
> hdparm -tT /dev/hda and hdc gives ...
>
> 1278MB/sec cashed reads
> 62MB/sec bufferd disk reads
>
> Which seems respectable for new 7200 Hitachi drives. (I did not setup DMA, my 
> BIOS did it for me) I was warned never to mix a HDD & a CD/DVD burner as it 
> degrades the HDD speed.
>
> I removed hdb and hdd, rebooted and did another hdparm -tT and got the same 
> results.
>
> I was going to install a PCI ATA controller for the two DVD drives but am 
> unsure now if it is worth it, can anyone comment (1st time RAID user :)
>
> Dave
>
>   

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