[mdlug] Reordeing IDE drives in a system

[Aaron Kulkis]

Dan Pritts wrote:
> On Tue, Oct 02, 2007 at 12:54:39AM -0400, Paul wrote:
>   
>> 	This later option solves the problem of re-ordered drives,
>> but with PATA drives you will need to make sure that they are
>> jumpered properly so they are all detected and dont step on each
>> other. Also, because two drives on the same controler channel
>> will have performance problems when doing a lot of I/O between
>> each other, ordering of PATA drives is usually a worthwhile
>> strategic endeavor. For example, having your main drive on hda
>> and your burner on hdb could cause problems during burning.
>>     
>
> not just between each other, but whenever both of them are in
> use.  Ideally, you just wouldn't use the slave, period, but
> if you hardly ever use the cdrom what the heck.

This is why I still like SCSI better than ATA (PATA and SATA)

ATA drives tie up the bus (ribbon cable) while the device is
doing the (mechanical) seek operation (head movement to the
correct track, and waiting until the sector comes around and
is read). In contrast, a SCSI device accepts the seek command,
disconnects, (letting other disk I/O traffic take place during
the seek), and then reconnects with the controller card once
it has read the data or is ready to write.

6 hard disks on a single SCSI channel isn't bad, and CD/DVD
devices aren't even a performance issue, because their
maximum bandwidth usage (by percent of total bandwidth
available on a SCSI channel) is so low.