Hard drive performances?

Matsaki

Matsaki

Registered
Is SCSI still the fastest hard drives available or can firewire compete this days. I heard about IDE with IEDE-buss, what is that?

So "if" SCSI is fastest, why would not Apple use them, specially in there server's?
 
Firewire is SCSI, it is just over a serial bus rather than a parallel one. The new G5s are using serial ATA which like an advanced IDE over a similar serial bus. They are both very fast. They have different pluses an minuses Firewire can handle more devices and I think it can have longer cables. SATA is limited to fewer devices but inside a single box that might not matter. I think that it is cheeper and it does have more commodity support.

If I remember right fibre channel is actually still faster and it is an option on the xserve, and it is another variation on SCSI...
 
S-ATA is at 150mb/sec
Firewire 800 at 100mb/sec
For a single drive this doesn't make any difference. Not even the 15000rpm spinning scsi drives can transfer more than 100mb/sec. EIDE is enhancedIDE which is quite old (UDMA33 was EIDE too). Anyway, in a raid system the bigger bandwidth makes sense. Eventhough the S-ATA is not that much faster than IDE (ATA133), it allows a much better handling since the cables are very thin and won't disturb the airflow for cooling.
Let's compare scsi and IDE now:
they are actually at the same speed when you compare the same spinning speeds for the disc. The fastest S-ATA (IDE) disc has 10000rpms. The fastest scsi is at 15000. Of course the scsi disc performs much better in latency time and data transfer. But this disc is very noisy and needs to be cooled. Anyway, in those days scsi had one very important advantage: the disc access was not wasting any processor work. But the current IDEs are using the processor at a very low level too. This is why I would definitely go for the inexpensive IDE drives (which by the way have much more disc space). If speed is desired and money a concern, I would go for raid IDE systems. And if speed is desired and money NO concern, I would take a closer look at scsi drives. ;)
 
This is solely my recommendation, of course, but you might want to take heed:

Do not, I repeat, do NOT get a SCSI setup for your Mac if it doesn't have it already. SCSI is probably one of the biggest pains in the ass I have ever had to deal with concerning computers. What's so bad about it, you may ask? Well, I'll tell you:
  • SCSI cables are the thickness of power lines and the length of a baby boy's pepe. I mean, come on—my mouse cable is longer than that!
  • You can only have 7 devices on a SCSI chain. After that, you need to get a new controller or something—don't know for sure, don't care to find out.
  • SCSI is hot-swappable—if you don't mind freezing your computer and possibly damaging your drives! In other words, you can't hot-swap SCSI drives at all.
  • SCSI drives require proper ID switch settings and termination. You have to set a switch on the back of each drive to give each device a unique SCSI ID, and I think they have to be in the correct order for the chain to work properly. Then you have to terminate the final device somehow.
  • I've counted, and there are actually 584 different types of SCSI connectors. Compare that to the, oh, 2 each for Firewire and USB.
  • SCSI drives are friggin' expensive! I mean, for the price of an 18 GB SCSI drive you can get an internal 100 GB IDE drive. And a decent one at that.
So, I hope for all these reasons you make the wise decision not to use SCSI if you can at all avoid it. Our G3 uses SCSI, and I must say it's quite a nightmare to try to add even one device, because I have to find cables with the right connections that are long enough to reach, and I have to set the chain ID's accordingly, and all that jazz.

Take it from me—
Avoid SCSI.
Go with IDE,
It's better. You'll see.

:D
 
I have not heard of SCSI 3 before. And I can't find what it looks like or how well it works. But there are already very fast standards used with Macs, and they are more compatible with OS X (I have heard that people have had problems trying to get OS X to recognize their SCSI devices on beige computers).
 
My old PentiumPro had SCSI3 back in the 90s it is not that new. They have gone away from the 1 2 3 numbering and I think the latest one was something like SCSI 340 or some such thing and that was a couple of years ago. The real future of fast buses are the serial buses like Firewire and SATA. Now that may sound contradictory because one would thing that you could move more data over 16 pipes than one. The problem is that as things go faster keeping the bits synchronized between the different pipes get too hard. It is actually faster to just send everything one bit at a time and not have to worry about keeping things synched.
 
How about large drives compared to small drives? A 250GB SATA drive compared to a 60GB SATA drive (both 7200RPM with 8MB cache). Will the 60GB be faster? How about when both drives are 80 - 90% full?

Also, do all firewire disks have regular ATA drives inside? I bought an empty bay and put a 120GB ATA drive in it... do manufacturers like Lacie do something similar?

Sorry for the barrage of questions :)
 
Fahrvergnuugen said:
How about large drives compared to small drives? A 250GB SATA drive compared to a 60GB SATA drive (both 7200RPM with 8MB cache). Will the 60GB be faster? How about when both drives are 80 - 90% full?

Also, do all firewire disks have regular ATA drives inside? I bought an empty bay and put a 120GB ATA drive in it... do manufacturers like Lacie do something similar?

Sorry for the barrage of questions :)
Click to expand...

The data density is much higher for the 250gb disc. By the same spinning speed, the 250gb disc will transfer more data. The latency should be nearly the same
 
Here's a few links for comparisons.

http://www.barefeats.com/hard30b.html

http://www.barefeats.com/hard29.html

I'm sure you could dig around there for all kinds of comparisons.

I've got one FW800 drive connected to a DP G4 (FW400 bus). The thing is freaking fast. I imagine it would be ridiculous on the G5s. I don't have any S-ATA connections yet, but all indications are that those are crazy fast also.

My understanding is that the very best/fastest is still SCSI at the very high and expensive end. But S-ATA and FW-800 are so close in speed (and much cheaper and easier to work with) that there's no point in going SCSI these days unless you absolutely, positively have to eek out every drop of performance and have a lot of money to burn.
 
andrefrancis2 said:
I don't understand very much of all this but .... wow ..... it is very impressive!
Click to expand...

Hehe, you know, I taught all these guys in here. If they didn't have me... man, this forum would be nothing :D ;)
Welcome to the forum andre!
 
You must log in or register to reply here.
Back
Top