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July 30th 16, 12:52 PM posted to alt.tv.tech.hdtv
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Thanks. I'm ripping DVD's to .mp4 files and transferring them to the external
drives which I hook up to my TV so all my movies are on the drive instead of
having to use the disks and DVD player. All is working as planned except when I
go to transfer from my desktop to the external drives. When I go to move a file,
it starts off at around 400-500 MB/s for a moment, then drops all the way down
to around 40MB/s. The external drives are WD My Books 4Tb drives, and rated at
USB 3.0. The cables are rated at USB 3.0 and my desktop is only a year old,
custom built, and all the USB ports, both on the MB, which is where the external
drives are plugged in, and also a PCI card with four USB ports, are all rated at
USB 3.0. In fact, the MB has two ports rated at and ready for USB 3.1. So I
don't know why the transfer speed is so low. At least I think it's low.
Ha, after looking around WD's website for any specs for that series of
drives (there isn't any, really), from the couple of recent posts to the
public forum, if you think it's doing 40MB/sec, count your blessings and
assume it's as good as it gets.
One guy said it takes 2 hours to copy a 3GB folder, another was saying it
seems to be 10x slower than some other drive he used to use. The only hard
numbers I ran across was it (My Book) uses a "green drive", which I think
automatically classifies it as a 5400RPM and "up to 3GB/sec" which probably
refers to the bus speed and or max for the drive on reads.
I do have one suggestion, I think you said you have a pair of them,
depending on what else is on the USB ports, have you tried it with just one
of them plugged in?
Not to go over the whole story but several years ago there was a discussion
in one of the mac groups about a particular model that had usb ports on both
the front and rear of it and if they were all on the same bus or if there
were two different controllers. Some people claimed if there was one in the
rear, one in the front, they seemed to be faster than if both were in the
rear (or front) ports.
This was all usb 2 so I don't know if it applies to usb 3 but after screwing
around and using a 1GB file to copy back and forth from an internal, what I
discovered was if there was only one drive on the bus, you did get close to
the max speed of 480mb/sec for usb2 and as soon as you plugged in another
drive, the speed almost halved. Write speeds went down to around 220mb/sec
and adding a 3rd and 4th pretty much reduced it to under 100mb/sec.
So since it wouldn't take much time or skill to test, why not just
disconnect all the usb devices except one of those 4TB drives and try a copy
to it and see if the speed improves any from where you are now.
If it does, it just seems to be another case of the usb anomaly with
multiple drives and if it doesn't, it's probably just a matter of those
drives being "low performance".
Honestly, I don't have usb3 anything here to test theories. After some
frustrating experience with firewire drives I switched to using an NAS over
gigabit ethernet and haven't looked back. Next best thing over internal
drives in my book.
All my "tv boxes" can see and mount the NAS over ethernet and just seems
easier to manage and use than a bunch of drives being moved around.
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