Make USB Flash Write Fast Again

I have a 64GB SanDisk Extreme USB flash drive that I use for just about anything. It is a USB 3.0 drive and at the time of purchase, it had the best performance out of all drives in the market.

I can’t remember how fast it was exactly when I first bought it but I remember the read speed was above 200 MB/s and write was above 150 MB/s. But yesterday, a year or so after purchase, I had write speeds of 20 MB/s sometimes falling to 6 MB/s. I wasn’t surprised as I knew at some point all the blocks will be written to and due to lack of support for TRIM, things will get slow — didn’t think that slow!

How do I know it doesn’t support TRIM? If I format and mount an FS with discard mount option and subsequently run fstrim /mnt where /mnt is the mount point of the volume, I get this: 

fstrim: /mnt: the discard operation is not supported

OK, but not all hope is lost. I knew about ATA Secure Erase command. What if that works? Turns out it does and it works so well. I followed the kernel guide but here is a summary of commands I ran (change /dev/X to appropriate dev) for the impatient. I strongly recommend reading the full guide.

WARNING as the name suggests, Secure Erase will delete all your data so be sure to make a backup first

  1. Set a user password (Nine is an example, you could use anything): 
    hdparm --user-master u --security-set-pass Nine /dev/X
  2. Make sure password is set successfully by checking if enabled is shown under Security section: 
    hdparm -I /dev/X
  3. Run the ATA Secure Erase command — mine took 10 seconds: 
    hdparm --user-master u --security-erase Nine /dev/X
  4. Verify that security is disabled 
    hdparm -I /dev/X

After the erase command, I did get an error but it worked nonetheless. Check the before and after graphs of gnome-disk-utility benchmark:

Screenshot of benchmark graph before ATA Secure Erase

This benchmark shows a very high average write speed compared to what I found (~ 20 MB/s) when copying data to the drive but you can see the horrible write speed irregularity. Also, this test took forever to finish.

Screenshot of benchmark graph after ATA Secure Erase

Mission accomplished.

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