Hard disc performance and DVD-ROM

Dear All. I have on 1st IDE channel a Maxtor Ultra ATA HDD as master and a DVD-ROM from Goldstar as slave. Before installing the DVD-ROM I have run a Sandra benchmark test on Maxtor and I have obtained very good results with drive index = 41 MB/sec and average access time = 9 ms. Then with DVD-ROM as the slave the same benchmark gave index = 14 MB/sec and aat = 22 ms. I ran the test for a second time and obtained index = 15MB/sec with aat = 9 ms. If I look at only aat then the conclusion is something went wrong in the first benchmark. But if I consider drive index, which is a good measure to have an idea on drive performance, then there is a real degradation. Does anyone have any experience on this subject? Can the presence of a DVD-ROM have such an edverse affect on the HDD? All advice is welcome. Thanks.

When having two devices sharing one channel (primary or secondary) you will see a drop in performance. This is due to the fact that the IDE channel only send one command at a time which often causes one of the drives to be forced to wait.

actually its not that. Its prooven that if you put an atapi device on the same cable as a hard drive it will degrade the hard drive performance.

The thing about IDE devices is you can only read or write to one device on the cable at a time.

That is why id rather have the cdrom and writer on the same cable than put one of them on the hard drive cable

Originally posted by LordOberon
The thing about IDE devices is you can only read or write to one device on the cable at a time.

That’s exactly what I just said!!!:confused:

Originally posted by Chriso
That’s exactly what I just said!!!:confused:

I think the confusion is in the way you typed it although you may know the answer to this. One can misinterpret what you typed by thinking that having more than one device per IDE channel degrades performance for each device.

“When having two devices sharing one channel (primary or secondary) you will see a drop in performance. This is due to the fact that the IDE channel only send one command at a time which often causes one of the drives to be forced to wait.”

This is not true in the event you have two HDD(obviosuly not a very old one <ata33) but lets say two ata100’s, there would be less than 1% drop in data transfer speed. If you have 1 HDD and 1 Optical on the other hand, the HDD will always drop its speed to that of the optical drive and thus be lowered significantly(close to ~33% drop in transfer speed.

Hope that clarified things up.:slight_smile:

Dear All. Thanks a lot for your reactions. After reading your comments I took away the DVD-ROM and left the Maxtor disc alone on the 1st IDE channel. Following the operation I ran the same benchmark on the drive. To my astonishment I am still getting the bad performance index = 13. I repeated the benchmark twice it is still the same. Now I can not understand what is going on. Perhaps if there are members of the forum who know the strenghts and weaknesses of the Sandra benchmark, they can help. Again any help is welcome. Thanks.

Originally posted by xtacydima
[B]I think the confusion is in the way you typed it although you may know the answer to this. One can misinterpret what you typed by thinking that having more than one device per IDE channel degrades performance for each device.

“When having two devices sharing one channel (primary or secondary) you will see a drop in performance. This is due to the fact that the IDE channel only send one command at a time which often causes one of the drives to be forced to wait.”

This is not true in the event you have two HDD(obviosuly not a very old one <ata33) but lets say two ata100’s, there would be less than 1% drop in data transfer speed. If you have 1 HDD and 1 Optical on the other hand, the HDD will always drop its speed to that of the optical drive and thus be lowered significantly(close to ~33% drop in transfer speed.

Hope that clarified things up.:slight_smile: [/B]

Thanks for clearing things up.:bigsmile:

Check to see if that controller is in udma or pio mode.

Originally posted by hwbee
Dear All. Thanks a lot for your reactions. After reading your comments I took away the DVD-ROM and left the Maxtor disc alone on the 1st IDE channel. Following the operation I ran the same benchmark on the drive. To my astonishment I am still getting the bad performance index = 13. I repeated the benchmark twice it is still the same. Now I can not understand what is going on. Perhaps if there are members of the forum who know the strenghts and weaknesses of the Sandra benchmark, they can help. Again any help is welcome. Thanks.

It is in UDMA 6. This is shown in Device Manager and also by Sandra.

I think I have found the reason for this degradation. At the beginning the harddisc on the 1st IDE was at UDMA 5 mode and the drive index was 41. Sandra gave a warning saying that these drives can go up to UDMA 6. So I installed the new SISIDE driver from ASUS which brought the 1st IDE to UDMA 6. At the same time I placed a DVD-ROM as slave on 1st IDE. Then the trouble started. Of course I thought that the trouble was coming from DVD-ROM, so I took it away and you know the rest of the story. Now I uninstalled this new SISIDE upgrade and the 1st IDE went back to UDMA 5. Result is I am now getting drive index 41 from the Maxtor 80 harddisc as before. Perhaps there is a logical explanation to this. But one thing is for sure the problem was coming from the new SISIDE driver which enabled UDMA 6 for the Maxtor harddisc, which in turn should have given a good performance. Amazingly this was not the case.

Originally posted by xtacydima
If you have 1 HDD and 1 Optical on the other hand, the HDD will always drop its speed to that of the optical drive and thus be lowered significantly(close to ~33% drop in transfer speed.

That is true for old hardware (2+ years old orso), these days IDE controllers use Independant Device Timing, meaning that 2 devices on the same IDE channel can run at different speeds, there’s one exception tho, which is when you connect a device that’s running in PIO mode, then the other device will run in PIO mode too.

Originally posted by hwbee
It is in UDMA 6. This is shown in Device Manager and also by Sandra.

What OS are you running?

Also, after you uninstalled the new IDE driver did you hook up the DVD-ROM as slave like you did before?

No, I did not install the DVD-ROM as before. I am glad that I have managed to recover the performance of the hard drive and now I do not dare to install the DVD-ROM on the same channel as slave. But, like many other power users , I like to experiment. On second thoughts I may try again to put the DVD-ROM and run a Sandra benchmark to see how much the harddisc performance will be affected. If I get new results and I shall post them.

Here is my configuration:
Win XP Home SP 1 (build 2600)
Mobo: ASUS P4S8X-X 133 megahertz
CPU: 2.40 gigahertz Intel Pentium 4
RAM: 512 MB
Primary IDE master Maxtor 6Y080L0
Secondary IDE master SONY DVD RW DRU-510A DVD/CD-Writer, slave PLEXTOR CD-R PX-W4012A
Dual Channel PCI IDE Controller (VIA VT6420 SATA IDE) master Maxtor 6Y160L0, slave Seagate ST340823A
Display: NVIDIA GeForce4 Ti 4200 with AGP8X