USB 3.0 Speeds

B

bubbagumper6

New Member
I have a regular 2.5" 5400RPM Sata HDD in an external enclosure with a USB 3.0 interface, however when I'm transferring files to it I'm not getting that great of speeds and they're also varying a lot. It will start out at over 100MB/s but then it will quickly shoot down to 80 and from there it will just slowly step down until it's around 35MB/s which is where it tends to stay. It probably takes about 30-60 seconds to get down to 35.

My question is, why do I see such good speeds at first but then it falls off?

This particular transfer was 18.3GB in 31 files but it was like 6 movies so the bulk of the size was only in those 6 files.

Also yes it's plugged into a USB3.0 port on my laptop.
 
I can't remember what speed USB3.0 is rated at but it's only the peak transfer rate, and sustained speeds are usually far lower. But it should probably still be fast enough not to be the cause...

It could be a fragmentation issue, especially if your drive is fairly full. Simply defragging the drive might help. Or in the unlikely event that you're using FAT32, it tends to get really slow after a while on large volumes so if this indeed is the case (I doubt it), back everything up and reformat as NTFS.

These are the only two possible causes that I could come up with that you actually have control over.
 
The drive is freshly formatted to NTFS so it was literally blank...

I'm not really using the drive to store things, only transfer large files between computers so once I've transferred the files I just erase them off the drive.
 
is it a powered drive, or does it draw its power from the USB3 port?
A drive that is lacking power may slow down to keep working.
 
ok. Whats the Sata interface on it? (1.5 or 3.0?). It could be that you are running into a HDD transfer speed ceiling on your drive.
 
SATA 1.5 transfers at 1.5 gigabits per second, not gigabytes.
1.5 gigabits= 1610612736 bits
35 megabytes is 293601280 bits.
so, your getting about as much as you can out of that drive right now. You could theoretically get a 192megabyte transfer speed, but you would most lkely end up frying the drive if you held it long.
 
It's also a 5400RPM drive which is not the fastest. If it was a 7200RPM and a SATA 3gbps or 6gbps model you'd see higher speeds, regardless of which USB interface you're using.
 
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