[GTALUG] some USB sticks are slow!

[D. Hugh Redelmeier]

I bought some inexpensive SanDisk Cruzer Glide 16GB USB sticks from 
Walmart last year.  Cheap.

Today I copied the CentOS 8 installation image onto one.

  time sudo dd if=CentOS-8-x86_64-1905-dvd1.iso of=/dev/sdg oflag=direct bs=16M

(I used a USB 3 port on my dessktop.)

It seemed to take a long time, so I did this to see if anything was 
happening (the dd process' PID was 29047):

  sudo kill -s USER1 29047

Yes, there was progress, but not as much as I would expect.  The final 
statistics were:

  425+1 records in
  425+1 records out
  7135559680 bytes (7.1 GB, 6.6 GiB) copied, 1560.63 s, 4.6 MB/s

  real	26m4.152s
  user	0m0.072s
  sys	0m4.706s

This amounts to about 4.56 MB/s.  That's even less than the poor
Average Sustained Write Speed 7.64 MB/s reported here:

  <https://usb.userbenchmark.com/SpeedTest/2718/SanDisk-Cruzer-Glide>

Note: this stick hasn't been written to often.  It should not be near the 
end of its life (that could slow down a flash device).