Will a slow hard drive decrease performance of a faster hard drive?

**ninjamyst** · May 3rd, 2004, 04:52 PM

Currently, I have a 40gig 7200rpm 2MB(master) and a 160gig 7200rpm 2MB(slave) on my computer. I just bought a 200gig 7200 8MB HD and want to replace the 160gig with it. If both harddrives are on the same IDE channel, will the slower 2MB decrease the performance of the faster 8MB? Given a 40gig 2MB and 200gig 8MB, what's the best possible setup? (I know I asked this a weeks ago but I am still confused as the difference between putting two harddrives on same ide channel vs different ide channel)

**osprey4** · May 3rd, 2004, 05:00 PM

I suppose the most obvious question is, why replace the faster drive?

Regarding performance, your proposed setup will be affected but not in a major way. The IDE bus is a bottleneck in that it can only read or write to one device at a time. So in the respect that reading/writing to the slower drive takes longer, this delays any reading/writing to the faster drive. Will you actually notice the difference? Probably not.

**John Prophet** · May 3rd, 2004, 05:15 PM

I dont think the 2mb or 8mb will affect the other drive.

The thing that will affect it is if one drive is an older, say, ata66 drive on the same cable with an ata133 drive.....they say that they both will run at ata66 speeds in that case.

of course i have heard that now it doesnt matter.

so I myself would like to see a definitive answer on this....cuz it does come into play if you put a DVD drive or cdrw on the same cable as a hard drive...cuz the cdrw's etc are usually ata66....so it would be nice to know if the cdrw is slowing the faster hard drive down.

Any benches or definitive articles out there??

**ninjamyst** · May 3rd, 2004, 05:42 PM

Originally posted by ninjamyst
Currently, I have a 40gig 7200rpm 2MB(master) and a 160gig 7200rpm 2MB(slave) on my computer. I just bought a 200gig 7200 8MB HD and want to replace the 160gig with it. If both harddrives are on the same IDE channel, will the slower 2MB decrease the performance of the faster 8MB? Given a 40gig 2MB and 200gig 8MB, what's the best possible setup? (I know I asked this a weeks ago but I am still confused as the difference between putting two harddrives on same ide channel vs different ide channel)

I am replacing the slwoer driver with the faster 8mb drive. Currently I have the 40gig as my primary but with a new 8mb one, I am wondering if it will be better to use the 200gig 8mb as primary and set the 40gig as a slave on either the same IDE channel or a different IDE channel

**Peter M** · May 3rd, 2004, 05:45 PM

Master/Slave setups ALWAYS degrade performance since IDE doesn't have any bandwidth sharing mechanisms. One drive working on something always completely blocks out the other one.

Put them on separate channels to solve this.

But no, the drives can very well run on different UDMA modes - if one is UDMA-133 and the other is UDMA-66, each will do its best when its turn comes. Only if you mix UDMA-66 (or higher) drives with UDMA-33 (or lower), you'll be kicked back to UDMA-33.

**John Prophet** · May 3rd, 2004, 06:08 PM

so what are cdrw and dvd drives nowadays?? are they still udma33??

**skuz** · May 3rd, 2004, 06:24 PM

Both my DVD drive and CDRW are UDMA33, so I put them on the same channel.

It amazes me that the most sold CD-ROM drive around here (LG) is still not UDMA compatible, only PIO4.

**Peter M** · May 5th, 2004, 08:18 AM

Originally Posted by skuz

Both my DVD drive and CDRW are UDMA33, so I put them on the same channel.

It amazes me that the most sold CD-ROM drive around here (LG) is still not UDMA compatible, only PIO4.

The LG drives can do DMA, MWDMA mode 2 to be exact. That's a 16 MB/s mode, plenty for any speed of CD-ROM. 1x speed being 150 KB/s, MWDMA mode 2 is enough for up to 100x CD-ROM drives.

Remember, again, there is no interface bandwidth sharing on IDE - so while your CD-ROM drive is being accessed, the other drive on the same cable is completely blocked out of doing something - no matter whether the CD-ROM drive is PIO mode 4 or UDMA mode 6.

Taking all this into account, putting a higher interface mode than MWDMA2 onto a CDROM drive is a pure marketing feature. Technically, it's pointless.