967 Views 6 Replies Latest reply: Jul 12, 2007 12:56 PM by Glyn Williams1
It seems to have a lot to do with the individual drive and/or USB controller in the external case.
I did a quick experiment after seeing slow writes to one of my USB drives.
First, I connected up a new Seagate 400GB SATA drive inside an Other World Computing Mercury Elite Pro external case using a high-quality USB cable. All should be state-of-the-art devices -- I paid $110 for the case and about $100 for the drive. Copying 11GB of data (mostly large video files) was calculated by Finder to take about 2 hours.
Then I connected a Maxtor 20GB IDE drive (3+ years old) inside a generic ($20) external case with the same high-quality USB cable. Copying the same files took only 45 minutes.
An observation: with the larger drive, there was a lot of disk activity (lots of clicking and clacking of the heads moving back and forth), but with the smaller drives, there was less noise. Perhaps the smaller drive is able to sustain longer writes.
Connecting both drives directly to the Mac via the USB cable, both took about 13 minutes to copy the files. Clearly, performance is related to interaction between the Airport Extreme and the drives.
There are a couple of variables I am unable, at this time, to eliminate. First, OWC case use SATA whereas the generic one uses IDE. I can't say whether this contributed to the problem.
Second, because of the interface issue, I cannot swap drives among the cases. That is, I can't put the 500GB drive into the generic case.
I may call OWC to find out if they know that a $20 generic USB case outperforms their $110 name-brand one.
Disk - WD MyBook. 500Gb - HFS - not journalled.
802.11b Powerbook G4 Reading - 410KBytes /s
802.11b Powerbook G4 Writing - 600KBytes /s
802.11g MacMini Reading - 1.5MegaBytes /s
802.11g MacMini Writing - 1.9MegaBytes /s
802.11n 5Ghz MacPro Reading - 5.2MegaBytes /s
802.11n 5Ghz MacPro Writing - 4.0MegaBytes /s