Olaf Marzocchi wrote:
> Every time I read something about optimizations of HDs I read "Put only 1
> HD per IDE bus".
> I think it is not so useful in modern buses, let's make an example.
> I have a 30 GB HD and a 20 GB HD in the same bus (unfortunately, it is only
> an example), the bus is ATA 66.
> Every disk can read at 20-25 MB when burst (I hope the syntax is correct),
> but normally they don't go over 13 MB (I'm very optimistic). OK, 2x13= 26
> MB/s, the bus is filled for less than a half. Let's imagine that in the IDE
> bus pass two times the data you really read, so 2x26=48 MB/s. The bus is
> still full for 3 quarters!! So WHY I should have to buy another controller
> when I don't fill the existing one???
> Could someone ansswer?
> Of course, I wouldn't put two drives @ 20 MB/s over an ATA/33, but nowadays
> I am the only one that still have those cards!!
In simple, basic, crude terms:
SCSI is multitasking, which means all devices can use the bus at the
same time. The speed limit is the SCSI bus limit. 3 24 Mb/S HDs will TP
around 70 Mb/S.
IDE is single tasking. One device must finish before another can use it.
The speed limit is the max speed of whatever device is making the others
wait. 2 40 Mb/S devices on the same channel will TP a max of 40 Mb/S
because only one can use the bus at a time.
--
For with much wisdom comes much sorrow; the more knowledge, the more
grief. Ecclesiates 2:8 NIV
Felix Miata *** http://mrmazda.members.atlantic.net/
