Quick question: are transfers faster between two hard drives on the same IDE cable or on different IDE cables?

[JonTheBaller]

Thanks!

 

[FishTankX]

Different cables. no interleaving. It's the same with CD burners too.

 

[MadRat]

If they share a cable then they share the bandwidth of the single channel.

If they use separate cables then they use independent channels tied to the same controller. You don't have to worry about UDMA channels being too fast for the controller anytime soon.

 

[Dufman]

imagine this

hard drive 1: source
hard drive 2: destination

on same chain: harddrive 1, must send data down the to the ide controller, and back up the chain to hd2, while hd1 is still sending data. the result is about 1/2 of max bandwith.

different chains: hd1 sends data to ide controller, through other stuff, then through the ide contoller that hd2 is hooked up, since data is pretty much flowing at 100% both ways. thus increasing performance,

 

[Maggotry]

Good information here. I just wanted to add that the problem is that the IDE controller can only address 1 device at a time on a channel. The controller will address the source to read, then address the destination to write. Using 2 channels (primary, secondary) you can read from one and write to the other at the same time.

This is one of the advertised advantages of the coming SATA spec. Each device will have it's own path. No more sharing master/slave settings on a channel. Essentially, every device will have it's own dedicated channel.

 

[thorin]

Only one drive can be 'talking' on the line at once. So having the source and destination drives on different channels is usually preferable (with current Parallel ATA [IDE] anyway).

Thorin

 

[Davegod]

the data has to go from the HDD down the cable to the mobo and right back up to the other one, and only one HDD can use the cable at a time.

Unfortunately they cant just go straight from one hdd along the cable to the next one. so like they said, different cables is optimal.

 

[Whitedog]

The difference is so small it's not even worth mentioning. Unless you're talking about transferring very large files, like 500MB+

I got bored, so tested a 260MB file here for kicks... take into consideration that not all these HD's are identical

Computer to Computer over 100Mb - 30Secs
HD0 to HD0 (Partition to Partition) - 15 Secs
HD0 to HD1 (Same Channel) - 14 Secs
HD0 to HD2 (Different Channels Same controller) - 11 seconds
HD0 to HD3 (Different Controller (on-board raid)) - 10 seconds

Also note that HD3 is a 100GB WD (fast HD) The others are 20 and 40 giggers... not as fast.

As you can see, it's really no big deal. In my opinion.

If HD2 were the same drive as HD3, I think the 12 seconds would be a little faster.

I thought it was interesting that the transfer was about the same going partition to partition as it was going from Drive to Drive on the same channel.

 

[thorin]

Ok now try this copy from one HD to another (A to B) while copying from one HD to another (B to A).

Edit: Clarification. Do same channel copy then cross channel copy.

Thorin

 

[Pariah]

Having 2 devices on the same IDE cable does not slow transfers down nearly as much as many would have you believe. Whitedog's numbers are further proof of that. If IDE could put more drives on a cable like SCSI it would make all the difference in the world, but with only 2 drives, neither of which can come close to maxing the interface by itself, it doesn't make much of a difference.

"Ok now try this copy from one HD to another (A to B) while copying from one HD to another (B to A)."

This doesn't test the efficiency of the interface. This tests the efficiency and access time of the drives. Another test would be to copy from A-B on the same channel, then copy from one partition on A to a 2nd partition on A. A-A will be much slower because mass reading and writing to the drive at the same time kills performance which is in essence what you are proposing.

 

[tart666]

It's faster to have two HD's on separate channels (if only one device per channel) 5-10% speed improvement. (133MB/s channel speed, 50MB/s max transfer speed each HD's, plus some collisions, etc)

In all real systems, however, CDROMs/CDRW/DVD drives will slow down your speed greatly if you put them on the same channel as your HD's. The mode will be limited to ATA 2 (33MB/s) instead of ATA 5.

Therefore, in all systems with CDROMs/CDRW/DVD drives present, it is better to put two HD's on the same channel. You lose 10% of speed instead of losing 75% of speed.

 

[LukFilm]

Originally posted by: tart666
It's faster to have two HD's on separate channels (if only one device per channel) 5-10% speed improvement. (133MB/s channel speed, 50MB/s max transfer speed each HD's, plus some collisions, etc)

In all real systems, however, CDROMs/CDRW/DVD drives will slow down your speed greatly if you put them on the same channel as your HD's. The mode will be limited to ATA 2 (33MB/s) instead of ATA 5.

Therefore, in all systems with CDROMs/CDRW/DVD drives present, it is better to put two HD's on the same channel. You lose 10% of speed instead of losing 75% of speed.

That's only the case IF BOTH OF THEM ARE WORKING AT THE SAME TIME. If you are using HD only, there will be NO performance penalty by having CD-ROM on the same channel.

 

[CraigRT]

the way i setup 2 hdd 2 cdrom is like this:

master hdd on primary IDE and a CD-ROM
and the next IDE just put either master hdd or master CD-ROM or burner... either way is fine.

IDE 1 - HDD, CD
IDE 2 - CD, HDD

thats how it should go..

 

[Whitedog]

IDE 1 - HDD, CD
IDE 2 - CD, HDD

That's usually what to avoid in my opinion. :Q But, to each his own...

 

[CraigRT]

Originally posted by: Whitedog
IDE 1 - HDD, CD
IDE 2 - CD, HDD

That's usually what to avoid in my opinion. :Q But, to each his own...

actually, honestly, me too.. that's what i used to avoid.
but it works better.
the transfer speeds i noticed are much better.
but thats just me... i mean, maybe for some reason it works better for you... i dont know.

 

[thorin]

Originally posted by: Whitedog
IDE 1 - HDD, CD (Burner)
IDE 2 - CD, HDD

That's usually what to avoid in my opinion. :Q But, to each his own...

Why?

Perhaps you're different then most people but the majority of users traffic is something like this:

1) Primary HD to Secondary HD (backups etc...)
2) CD to Primary (software installs)
3) CD to Burner (DAE & CD "Backup" )
4) Secondary HD to Burner (archive etc....)

Making the above setup the most efficient.

Thorin

 

[Brian48]

I find the following to give me the best compromise between overall HDD speed, DVD playback, and on-the-fly CDR burning. Especially for the later two.

IDE1:
HDD - P.Master
CDRW - P.Slave

IDE2:
HDD - S.Master
DVDROM - S.Slave

 

[Whitedog]

I don't use more than one IDE drive anyway in my PC, so my opinion really doesn't count now does it.

My setup is HD on Channel 1 (1200JB), DVD and CDRW on Channel 2.

Also, I never do anything like CD Copying (drive to drive)... At least from my DVD to CDRW drive. My DVD player doesn't read sub-channel data correctly, so I just use my Burner to read everything, but I only read it to a file and save the disk images... If I need to make another disk, I just do it from the image. (all of my CD Images are kept on my server, which has 4 SCSI drives in it)

I never use the ROM drives for running programs, I just mount images to a virtual drive and run them from there.... Always!
I have 37 CD Images on my server and can mount 8 to 12 virtual drives at a time. It rOxOrZzz

So again, how my system is hooked up doesn't matter in this case.

 

[rbV5]

In all real systems, however, CDROMs/CDRW/DVD drives will slow down your speed greatly if you put them on the same channel as your HD's. The mode will be limited to ATA 2 (33MB/s) instead of ATA 5.

Thats not true for most systems with modern IDE controllers. Most IDE controllers allow different transfer rates on the same channel and will not default to the transfer rate of the slower device.

 

[thorin]

Originally posted by: rbV5

In all real systems, however, CDROMs/CDRW/DVD drives will slow down your speed greatly if you put them on the same channel as your HD's. The mode will be limited to ATA 2 (33MB/s) instead of ATA 5.

Thats not true for most systems with modern IDE controllers. Most IDE controllers allow different transfer rates on the same channel and will not default to the transfer rate of the slower device.

Yes unless you have one of the very earliest generation mobo's with mixed ATA33/66/100 then you'll be fine. All current devices (mobos and drives) support Independant Device Timing.

Ummm ya whitedog I guess your setup isn't exactly average joe heh

Thorin

 

[merlocka]

Originally posted by: thorin

Originally posted by: Whitedog
IDE 1 - HDD, CD (Burner)
IDE 2 - CD, HDD

That's usually what to avoid in my opinion. :Q But, to each his own...

Why?

Perhaps you're different then most people but the majority of users traffic is something like this:

1) Primary HD to Secondary HD (backups etc...)
2) CD to Primary (software installs)
3) CD to Burner (DAE & CD "Backup" )
4) Secondary HD to Burner (archive etc....)

Making the above setup the most efficient.

Thorin

Very informative thread, thanks.

So... I'm thinking about my next Mobo and trying to decide if I need an additional IDE controller on it (Raid or SATA Raid). I currently have Raid but just use it to give each drive it's own channel. I haven't really noticed any performance improvements over running everything from one controller.

My question is why do you suggest the second HD is slave on secondary IDE? Thx.

 

[Pariah]

"All current devices (mobos and drives) support Independant Device Timing.'

Except Intel in some situations. The fact that Intel admits this makes you wonder about the other manufacturers.

"I haven't really noticed any performance improvements over running everything from one controller."

And you shouldn't, because there really isn't much difference.

"My question is why do you suggest the second HD is slave on secondary IDE? Thx."

It doesn't really matter either way. Beyond putting your boot drive on primary master, which even this isn't required with some boards today, it doesn't really matter how everything else is arranged. There was a time when certain devices like DVD drives and CDRW drives were very finicky about where they were (master setting gave fewer problems), but anything reasonably current should not have any issues.

 

[Demon-Xanth]

This brings up an interesting question, can SCSI-SCSI transfers on the same cable be faster than if they were on seperate channels? I don't remember if SCSI devices can talk to eachother directly or if they have to go though the host.

 

[corkyg]

It really depends on what you are doing and how. For the past few years I have always had two HDDs on the primary channel, because only 1 is used. The other is a hidden backup. To clone drive 1 to 2 works great, and then either can be hidden. The secondary IDE channel is my DVD player and LS-120. All my burners are external Firewire or USB 2.

I clone my backup drive once a week or sooner if major changes or new software is added. Then I can hide the source and boot from the target for a week. That gives each drive a week off every other week. Mobile racks can be used to provide on and off switching, then one does not need to hide a drive. Or, using Romtec's Trios II, they can be selected on a controller pad. I have done all of them.

 

[Whitedog]

can SCSI-SCSI transfers on the same cable be faster than if they were on separate channels?

SCSI devices are nothing like IDE; they can all be access (Read/Write) simultaneously. The reason you don't here too much about it though is because of the $$$...

To get good IDE performance, all you have to buy is 1 HD = <$200 for TONS of disk space...

To get a basic SCSI setup you have to buy a card (single channel U160 runs about $120-150). A "descent" 73GB SCSI drive will cost you $300. You would have to get two of these drives to get the disk space of the IDE setup... So you're at $700+ just for disk space...

Not too many people care to part with that much cash for disk space...

Don't think I have a lot of money because I have 4 SCSI drives in my server... they are small, and old. (9, 18, 18, 18)

If money were no object, you would definitely want to go with SCSI. Bar none.