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reemas · Nov 9, 2005, 05:50 PM

I have to decide between a FW800 and FW400 hard drive enclosure. I wont be using FW800 just yet because the iMac doesn't support it. But thinking ahead, is FW800 going to be something that is common like FW400 today?

I ask because I don't see much support for FW800 products, or even Firewire. USB 2.0 seems to be taking over, including Apple's iPods.

mduell · Nov 9, 2005, 06:51 PM

Firewire 800 is in the awkward position of being way too fast, or too slow. The only thing that it's "about right" for is single external hard drives.
For multiple drive enclosures, it's too slow (two drives can easily push more than FW800 can take); for everything else (cameras, scanners, video cameras, PDAs, music players, optical drives) it's overkill in terms of size/speed/power consumption.

I'd go with FW400 for now, since that's all you can use with your iMac. If you buy a computer with FW800 in the future, FW800 enclosures will probably be much cheaper by then (i.e. the price of a FW800 enclosure today is higher than the price of a FW400 enclosure today and a FW800 enclosure in the future).

reemas · Nov 9, 2005, 07:56 PM

how would it work for a raid0 (mirroring) setup? thanks for the info by the way.

mduell · Nov 9, 2005, 08:42 PM

RAID0 (striping) or RAID1 (mirroring)?
Across two external disks or across your internal disk and an external disk?

RAID0 of two external disks: If the two FW400 ports are on different channels this could give you good performance. If both ports are on the same channel then it's pointless because one disk can saturate the bus already. I'm not sure if the two FW400 ports on the iMac share a channel or not. Keep in mind that if you wanted to get any data off it both disks would have to be plugged in (so you couldn't plug in a video camera or similar).

RAID0 of the internal disk and an external disk: Really weird and not a great idea, because you could never disconnect the external disk.

RAID1 of two external disks: If the two FW400 ports are on different channels this could get the same performance as a single disk, but with the obvious advantage of data redundancy. If both ports are on the same channel then the performance would be pretty terrible, but at least you'd have two copies of your data. I'm not sure if the two FW400 ports on the iMac share a channel or not. Keep in mind that if you wanted to get any data off it both disks would have to be plugged in (so you couldn't plug in a video camera or similar).

RAID1 of the internal disk and an external disk: Again, weird, but this time at least you can disconnect the external disk and still have your computer run. Sort of an odd way to do a half-assed backup; not a real backup since you can't recover deleted files (they'd be deleted from both drives simultaneously).

reemas · Nov 10, 2005, 02:07 AM

Mark,
Great info again. I think I will go with this setup: RAID1 Mirroring with two external hard drives in one enclosure. There is a FW800(2) and FW400(1) port(s) on the enclosure. Unfortunately the iMac won't have FW800, but this is the only RAID case I found:
http://eshop.macsales.com/item/Other...ng/MEFW912AL2/

I plan on using FW400 to connect the enclosure to the iMac and daisy chaining this enclosure with another enclosure through FW800.

Since the enclosure only has 1 FW400 port, can I plug this into 1 port on the iMac for RAID1 Mirroring ? There are not two FW400 ports.

mduell · Nov 10, 2005, 09:44 AM

I'm not sure if you can daisy chain with the FW400 and FW800 ports. It may work with thw FW400 and FW800 ports or you may need to buy a cable with FW400 (6 pin) on one end for the iMac and FW800 (9 pin) on the other end for the enclosure and connect the other device to the other FW800 port. Unfortunately the page you linked to doesn't mention anything about daisy chaining.

Yes, you can plug it in via FW400 and use both disks in RAID1. The page you linked to says it supports hardware RAID, but the instructions page looks more like software RAID to me.
If it is hardware RAID you'll be limited to 50MB/sec in theory for reading and writing; in reality you can expect to see 30-40MB/sec. For comparison that's about as fast as an average 2 year old desktop drive.
If it is software RAID you'll be limited to 25MB/sec in theory and 15-20MB/sec in reality. For comparison that's about as fast as an average 1 year old laptop drive.

reemas · Nov 11, 2005, 12:03 AM

Mark I need some help. Here's my current setup.
FW800/400 Case with a 250GB drive.
FW800/400 Case with a 400GB drive.

If I connect one external drive to my powerbook via fw800 and then connect it to the other external via fw800 also, I can transfer a 575MB file from drive to drive in 16 seconds. And I can transfer the same file from Any drive to and from my Powerbook's drive in 30 seconds. (makes sense since the pb has a slower drive).

However, if I connect an enternal drive to my powerbook via fw400 and then repeat the rest of the setup, all transfers take 30 seconds. even drive to drive (which is still fw800 to fw800) takes 30 seconds now.

I find that strange because the two externals are hooked up via fw800 as in the first case. Why does it matter what is plugged into my powerbook?

(oh and if you're wondering why I'm plugging fw400 into my pb, its because soon i'll have an imac with only fw400). i want to have optimal trasnfer speed amongst the two external hard drives.

hope you followed!

inkhead · Nov 11, 2005, 12:15 AM

there is no ata, sata, drive that can use the full bandwidth of fw800, fw400 or even usb2.

Just get a usb2 enclosure or a hybrid enclosure usb/firewire and forget about it.
.

reemas · Nov 11, 2005, 01:42 AM

I didn't know that inkhead. Thanks for the tip.

However, I will be transferring data heavily between the two externals and would def. like to have it twice as fast, as noted in the times about. (those were avg. times of many tests.)

So if anyone knows why that was the case please let me know. Thanks to all.

mduell · 02:52 AM

Originally Posted by reemas

Mark I need some help. Here's my current setup.
FW800/400 Case with a 250GB drive.
FW800/400 Case with a 400GB drive.

If I connect one external drive to my powerbook via fw800 and then connect it to the other external via fw800 also, I can transfer a 575MB file from drive to drive in 16 seconds. And I can transfer the same file from Any drive to and from my Powerbook's drive in 30 seconds. (makes sense since the pb has a slower drive).

However, if I connect an enternal drive to my powerbook via fw400 and then repeat the rest of the setup, all transfers take 30 seconds. even drive to drive (which is still fw800 to fw800) takes 30 seconds now.

I find that strange because the two externals are hooked up via fw800 as in the first case. Why does it matter what is plugged into my powerbook?

If I recall correctly the Firewire spec, downstream devices on a daisy chain can't operate faster than the slowest upstream speed (FW800-and-better networks may be different since they allow for loops). The FW800 ports between the two can only operate at FW400 speeds when connected via FW400 to the PowerBook.

Originally Posted by inkhead

there is no ata, sata, drive that can use the full bandwidth of fw800, fw400 or even usb2.

Just get a usb2 enclosure or a hybrid enclosure usb/firewire and forget about it..

Absolutely untrue! My year-old 160GB SATA drive can push 57MB/sec, which exceeds the theoretical bandwidth of FW400 (50MB/sec) and the practical bandwidth of USB2 (~45MB/sec). Storagereview's performance database has a number of SATA drives in the 60-72MB/sec range, which is nearing the practical bandwidth of FW800.