DJW said:
Can I put a hard drive on a secondary IDE ATA bus? Is an old ata hed disk and am I right that it will be slowed down a bit in read write speeds. I want to put it in as a slave and the master on that second bus is a CD-RW drive.
If you have any pet theories, you can put them to the test
with an HDTune read benchmark.
Run your hard drive on your "best" bus first, to establish
a baseline graph. You should get a smooth, declining curve.
If the curve has significant flat areas, that can
represent a "bus bottleneck", possibly a cabling or
interface speed issue.
You can see in my comparison here, of SATA running at
SATA I or SATA II, what "clipping" of the curve looks
like when the bus is too slow (upper graphs). At the
very beginning of the graph, the cable rate is limiting
sustained transfers.
http://img829.imageshack.us/img829/842/500gb3500418ascomposite.gif
Then use your suspicious "secondary" IDE, connect one or
two devices to the cable, and repeat the HDTune test. What
did you see ?
I'm willing to bet, no difference. The two devices are
supposed to be independent on the cable.
(If one of these links doesn't render right, try the other.
Page uses old style frames.)
http://www.pcguide.com/ref/hdd/if/ide/conf_Performance.htm
http://www.pcguide.com/ref/hdd/if/ide/confPerformance-c.html
"Independent Master/Slave Device Timing:
Hard disk controllers on modern systems support running
the master and slave device at different speeds, if one
supports faster transfer modes than the other. Some systems,
however, especially older ones, do not. If you are using
two devices with radically different maximum transfer rates,
and the chipset doesn't support independent timing, you will
slow down the faster device to the speed of the slower one."
Now, the paragraph next to that, is a bit disturbing.
"Hard Disk and ATAPI Device Channel Sharing: There are
several reasons why optical drives (or other ATAPI devices)
should not be shared on the same channel as a fast hard disk.
ATAPI allows the use of the same physical channels as IDE/ATA,
but it is not the same protocol; ATAPI uses a much more
complicated command structure. Opticals are also generally
much slower devices than hard disks, so they can slow a hard
disk down when sharing a channel. Finally, some ATAPI devices
cannot deal with DMA bus mastering drivers, and will cause a
problem if you try to enable bus mastering for a hard disk on
a channel they are using."
I can understand a comment about performance, in terms
of the slow optical device occupying the bus for relatively
long periods of time, if both the optical and hard drive
are accessed at the same time. But in my experience, with
modern gear (where the optical and the hard drive, are
both using DMA modes), I feel the first paragraph applies.
As far as I know, a modern optical and modern hard drive,
support independent timings.
And you can prove this for yourself, and for the world,
with some HDTune benchmarks. Don't take my word for it.
The free version of this, is good enough for cable
rate testing, with optical installed or not installed,
with optical as master or as slave (the other device
being jumpered for the opposite of the optical).
http://www.hdtune.com/files/hdtune_255.exe
Paul