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Old 01-05-2014, 09:03 AM   #1
cubathy
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Registered: Jan 2014
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Diagnosing poor performance on ext4 USB drive


Hi all - after some help investigating an issue I am seeing with one of my external USB drives.

I have 4 1TB ext4 USB2 drives (all identical hardware) mounted through a USB hub. 3 of them perform well enough, but one is very slow for reads and writes (see hdparm timing output below).

Examining the output of hdparm -I shows no differences between the drives (except identifiers) and I couldn't see anything interesting in lsusb -v. Any clues on how to go about investigating this would be appreciated. I'm running Linux Mint 12 Maya.

Bad disk:
Code:
> sudo hdparm -tT /dev/sdd1
/dev/sdd1:
 Timing cached reads:   602 MB in  2.00 seconds = 301.02 MB/sec
 Timing buffered disk reads:   4 MB in  3.65 seconds =   1.10 MB/sec
Other disks:
Code:
> sudo hdparm -tT /dev/sdb1
/dev/sdb1:
 Timing cached reads:   4940 MB in  2.00 seconds = 2471.84 MB/sec
 Timing buffered disk reads:  94 MB in  3.01 seconds =  31.20 MB/sec
Thanks
 
Old 01-05-2014, 10:47 AM   #2
jefro
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I'd guess that just because they are in similar boxes, they have different parts somewhere.

I'd think about swapping the hard drive in two of them to see if it follows the drive. If not then it has to be an issue with the circuit on the enclosure. Maybe some buffer not correct from factory or could be any number of connector issues. Some might be swapped to test.

Swapping is the only way I know of to help narrow it down.
 
Old 01-07-2014, 03:54 PM   #3
cubathy
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Registered: Jan 2014
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Managed to solve this in the end by fixing some bad sectors, running:

Code:
sudo fsck.ext4 -dft -C 0 /dev/sdd1
 
Old 01-07-2014, 09:40 PM   #4
jefro
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Thanks for the solution.
 
  


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