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When I copy big files ( > 300MB ) from hard drive to SD-Card, copying slows dramatically after first 400mb, sometimes the copy process never ends.

I tried copying with double-commander, rsync (with progress indicator), and cp.

my setup:

  • ubuntu 16.04
  • microSD card, partition formatted to VFAT, 64GB total, 50GB, available

copying starts at 15 MB/s, and after ~400MB drops to nearly zero, after few minutes it can "randomally" resume, and slow again.

Even when it reaches 100%, the program will "freeze" for several minutes until it concludes writing.

Why is that?

Can I speed it up?

Will eXfat/NTFS solve it? (I need compatibility with windows).

Berry Tsakala
  • 161

1 Answers1

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Watch a slow memory card or USB drive

The drive might not be broken, only very slow. This will be shown, when the caching is full of 'dirty' data (not yet written to the drive).

There is a small tool, watch-flush, bundled with mkusb, that can be used as a stand-alone shellscript in order to watch writing also with other tools than mkusb.

Start sync to tell your system to flush the buffers, and watch the process with watch-flush.

Wipe the whole device

If your memory card or USB pendrive is very slow, it might get more responsive after you wipe the whole device (overwrite with zeroes) using mkusb.

Check if there are more severe problems

You can analyze the problem and if you are lucky solve it according to the tips in the following link,

Analysis of the problem

sudodus
  • 6,421