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View Full Version : Does dasiychaining firewire devices affect performance?




nylon
Apr 15, 2006, 05:32 PM
I'm planning on daisy-chaining a dvdrw and hard drive together since my MBP only has one firewire port.

Will burning disks be affected if I am simultaneously accessing the firewire HD or vice versa over the same firewire 400 bus.

I'm trying to avoid purchasing a hub.



Patmian212
Apr 15, 2006, 05:42 PM
I am not 100% sure but I would say yes simply because the firewire bus has a limited amount of bandwidth and it will be shared between the two devices.

Kingsly
Apr 15, 2006, 05:58 PM
I dont think daisy chaining is any different from a hub, bandwidth wise. I know DV takes up about 3.7 MB/s. I daisy chain my XL-1 with my storage drive and capture video to it all the time. Im only using 3.7x2 MB/s, or 7.4 of 400 MB/s. So no, as long as you dont use more bandwidth than FW can give, it wont affect performance. I think. :D

nylon
Apr 15, 2006, 08:24 PM
Well that offers two completely opposing views, not that I don't appreciate it. Anyone else care to chime in.

matticus008
Apr 15, 2006, 09:00 PM
It depends on whether your hardware is good quality or not, but assuming the controllers are up to par, you will be able to use both devices seamlessly. If you had more than two devices attached, you would eventually run into performance problems...Firewire can fall apart completely if overloaded with requests for bandwidth, but a DVDRW and a hard drive won't max anything out.

nylon
Apr 15, 2006, 11:03 PM
Thanks, that gives me some reassurance.

mduser63
Apr 15, 2006, 11:12 PM
I dont think daisy chaining is any different from a hub, bandwidth wise. I know DV takes up about 3.7 MB/s. I daisy chain my XL-1 with my storage drive and capture video to it all the time. Im only using 3.7x2 MB/s, or 7.4 of 400 MB/s. So no, as long as you dont use more bandwidth than FW can give, it wont affect performance. I think. :D

DV is actually around 25 Mbps (as opposed to MBps, which is 8 times more), still much less than Firewire supports.

generik
Apr 16, 2006, 04:27 AM
How about 2 x EyeTV 410s?

simie
Apr 16, 2006, 05:17 AM
I have EyeTv daisy-chained to DVD writer and there is no performance loss with either.

steve_hill4
Apr 16, 2006, 05:23 AM
DV is actually around 25 Mbps (as opposed to MBps, which is 8 times more), still much less than Firewire supports.
25Mbps is 3.125MBps, (a Byte is 8 bits, not the other way around), so the initial figure of 3.7MBps is almost the same as the corrected figure you posted.

However, when you take into account error detection/correction and audio, it comes to 36Mbps. That equates to 4.5MBps.

howesey
Apr 16, 2006, 06:08 AM
25Mbps is 3.125MBps, (a Byte is 8 bits, not the other way around), so the initial figure of 3.7MBps is almost the same as the corrected figure you posted.

However, when you take into account error detection/correction and audio, it comes to 36Mbps. That equates to 4.5MBps.
Is that 36MB/s or 36MiB/s?

matticus008
Apr 16, 2006, 06:31 AM
Is that 36MB/s or 36MiB/s?
Neither. It's 36Mb/sec.

mduser63
Apr 16, 2006, 09:30 AM
25Mbps is 3.125MBps, (a Byte is 8 bits, not the other way around), so the initial figure of 3.7MBps is almost the same as the corrected figure you posted.

However, when you take into account error detection/correction and audio, it comes to 36Mbps. That equates to 4.5MBps.


Yes, but FireWire supports 400 Mbps, not 400 MBps like Kingsly posted.