Slow USB Hard Drive

sechs

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#1
I've been collecting used external 2.5" harddisks with the intention of cracking them out of their USB enclosures and using them in a new NAS that I'm building. Unfortunately, once I shuck the drives, the warranty is kaput; so I need to to try to determine any problems before opening them up.

I have two Seagate externals which pass Seatools, but are incredibly slow. Seatools expects the long test to take about six and a half hours; it takes the better part of a day on these drives. On one of the drives, a file copy shows the speed constantly going up and down. Right now, I'm doing a long format on that drive to see if that clears up any bad blocks that it may have. I have other drives of the same model that seem to work great, so it really is just these two.

Is there anything else that I can do to either clear up this problem or trigger it to error so that I can RMA them?
 

LunarMist

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#2
I've been collecting used external 2.5" harddisks with the intention of cracking them out of their USB enclosures and using them in a new NAS that I'm building. Unfortunately, once I shuck the drives, the warranty is kaput; so I need to to try to determine any problems before opening them up.

I have two Seagate externals which pass Seatools, but are incredibly slow. Seatools expects the long test to take about six and a half hours; it takes the better part of a day on these drives. On one of the drives, a file copy shows the speed constantly going up and down. Right now, I'm doing a long format on that drive to see if that clears up any bad blocks that it may have. I have other drives of the same model that seem to work great, so it really is just these two.

Is there anything else that I can do to either clear up this problem or trigger it to error so that I can RMA them?
At some point Seagate started using the shingled format in their 2.5" external drives and that is typical behavior for them. The older Seagate 2.5" drives were mainly based on the Samsung design.
 

sechs

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#3
Based on their ages and reported details, all of the drives that I have should be SMR. That's not the problem.

I set the drive that I reformatted yesterday to run a copy of ~1TB. The initial write speed varied wildly, even going all the way to zero. About a quarter of the way through, the drive disconnected.

When I pulled the USB cable and reconnected it to the drive, it came right back. I restarted the copy, but the speed to going up and down in exactly the same way.

I suspect that it's actually the SATA-to-USB board on the drive that a problem, but there's no way to be sure about that without testing the bare drive.
 

LunarMist

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#4
I only have a copule of the Backup Plus 2TB with the shingles or whatever else makes them intermittently slow.
Which are yours?
 

sechs

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#5
They're all Seagate Slim or Expansion drives. I got in two drives yesterday that are older and are clearly PMR drives (they're slower and have a smaller cache); the rest are SMR.

After a bit of research, it seems like a lot of folks are having trouble with USB devices disconnecting in Windows 10 with USB 3.0 ports. So, I've taken one of the problem drives to another machine and am testing it on a USB 2.0 port. Other than going about half the speed, it's shown no problems.

If this is the problem, I'm a bit confused as to why some drives would suffer from these issues, but not others.
 

LunarMist

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#6
They're all Seagate Slim or Expansion drives. I got in two drives yesterday that are older and are clearly PMR drives (they're slower and have a smaller cache); the rest are SMR.

After a bit of research, it seems like a lot of folks are having trouble with USB devices disconnecting in Windows 10 with USB 3.0 ports. So, I've taken one of the problem drives to another machine and am testing it on a USB 2.0 port. Other than going about half the speed, it's shown no problems.

If this is the problem, I'm a bit confused as to why some drives would suffer from these issues, but not others.
I'm confused. I thought the SMR drives were slower and funky. Of course they have higher platter density, but do they maintain speed over a full drive write? How long does it take to encrupt a whole drive?
The ones I have slow down after 20 GB or some amount that I forget and are erratic thereafter.
 

sechs

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#7
SMR drives are slower than comparable PMR drives. Seagate generally tries to mitigate this with a larger cache and a PMR section of the disk for fast writes. After you exhaust these, you'd see a dip in write speed.

In my experience, the PMR drives have a steady write speed but average lower than that SMR drives. The SMR drives vary pretty widely in write speed but average higher.
 
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