Re: usb3 sticks do not seem to work properly.

From	"Carlos E. R." <robin_listas@es.invalid>
Newsgroups	alt.os.linux.mageia, alt.os.linux
Subject	Re: usb3 sticks do not seem to work properly.
Date	2019-02-11 22:28 +0100
Message-ID	<gce7nkFp1v2U1@mid.individual.net> (permalink)
References	<q3s8lo$5f6$2@dont-email.me>

Cross-posted to 2 groups.

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On 11/02/2019 17.42, William Unruh wrote:
> I am trying to install Mageia onto usb sticks, both usb2 and usb3
> sticks. 
> I am installing by doing 
> dd if=Mageia-7-cauldron-x86_64.iso of=/dev/sdb bs=1M status=progress
> and both usb2 and usb3 take a long time to install. Both start of fast,
> but finally settle down to 10MB/s writing, so the writing takes almost
> an hour. I thought usb3 was supposed to be fast. This is the same on my
> laptop  (which has usb3 ports and MGA6) and the new desktop( Ubuntu 18).

Write speed on USB sticks is simply slow, no matter if they are USB 2 or
3. When you buy sticks you have to look at the sustained write speed if
they say it. If it is USB 3 they will boast that number if it is good,
and say nothing if it is bad.

Yes, initially the write seems to be fast because the kernel is caching
the operation in memory. At the end, you may notice that the dd command
exits but the stick LED is still flashing - while the cache is emptied.

Use this command instead:

 if=ISO of=DEV bs=16M oflag=direct status=progress

It usually works better by not slowing the rest of the system, not tying
cache memory that is not going to be used again, and instead using RAM
on the dd itself.

> The big problem is that when I want to check tha tthe writing has
> worked, I do 
> md5sum /dev/sda
> and it takes about 1/2 hour to check the 4GB content of the stick, and
> persistantly, whether I used usb2 or usb4 sticks, the check sum is NOT
> the same as original file.  The sticks all have plenty of room ( they
> are either 16 or 32GB sticks) Furthermore the checksum changes if I run
> md5sum again on the same stick with nothing done to it.

Normally doing this check is pointless - you don't do this every time
you copy a file on hard disk. The check is important when writing to
DVD, because there the write failure rate is large.

Further, the checksum of /dev/sda is not the same as the checksum of the
ISO image, because they have different size. You have to do a file
compare instead and limit the number of bytes. Maybe dd from stick a
number of bytes to a pipe to md5sum.

-- 
Cheers,
       Carlos E.R.

Thread

usb3 sticks do not seem to work properly. William Unruh <unruh@invalid.ca> - 2019-02-11 16:42 +0000
  Re: usb3 sticks do not seem to work properly. Mike Easter <MikeE@ster.invalid> - 2019-02-11 08:56 -0800
  Re: usb3 sticks do not seem to work properly. Richard Kettlewell <invalid@invalid.invalid> - 2019-02-11 18:50 +0000
    Re: usb3 sticks do not seem to work properly. William Unruh <unruh@invalid.ca> - 2019-02-11 22:45 +0000
      Re: usb3 sticks do not seem to work properly. Jasen Betts <jasen@xnet.co.nz> - 2019-02-12 01:59 +0000
      Re: usb3 sticks do not seem to work properly. Richard Kettlewell <invalid@invalid.invalid> - 2019-02-12 08:45 +0000
        Re: usb3 sticks do not seem to work properly. Paul <nospam@needed.invalid> - 2019-02-12 05:50 -0500
        Re: usb3 sticks do not seem to work properly. William Unruh <unruh@invalid.ca> - 2019-02-12 16:03 +0000
          Re: usb3 sticks do not seem to work properly. Bit Twister <BitTwister@mouse-potato.com> - 2019-02-12 10:20 -0600
            Re: usb3 sticks do not seem to work properly. Peter Pearson <pkpearson@nowhere.invalid> - 2019-02-12 17:55 +0000
          Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-12 13:56 -0500
            Re: usb3 sticks do not seem to work properly. Richard Kettlewell <invalid@invalid.invalid> - 2019-02-12 19:18 +0000
              Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-12 14:59 -0500
          Re: usb3 sticks do not seem to work properly. Richard Kettlewell <invalid@invalid.invalid> - 2019-02-12 19:15 +0000
  Re: usb3 sticks do not seem to work properly. Wes Newell <w.newell@tx.rr.com> - 2019-02-11 20:27 +0000
  Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-11 15:32 -0500
    Re: usb3 sticks do not seem to work properly. faeychild <faeychild@afraid.org> - 2019-02-12 08:32 +1100
    Re: usb3 sticks do not seem to work properly. William Unruh <unruh@invalid.ca> - 2019-02-11 22:49 +0000
      Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-11 21:49 -0500
        Re: usb3 sticks do not seem to work properly. Paul <nospam@needed.invalid> - 2019-02-11 22:15 -0500
    Re: usb3 sticks do not seem to work properly. Jasen Betts <jasen@xnet.co.nz> - 2019-02-12 02:03 +0000
      Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-11 22:15 -0500
        Re: usb3 sticks do not seem to work properly. "Carlos E.R." <robin_listas@es.invalid> - 2019-02-12 05:22 +0100
  Re: usb3 sticks do not seem to work properly. "Carlos E. R." <robin_listas@es.invalid> - 2019-02-11 22:28 +0100
  Re: usb3 sticks do not seem to work properly. Paul <nospam@needed.invalid> - 2019-02-11 18:52 -0500
    Re: usb3 sticks do not seem to work properly. ant@zimage.comANT (Ant) - 2019-02-11 21:47 -0600
      Re: usb3 sticks do not seem to work properly. William Unruh <unruh@invalid.ca> - 2019-02-12 04:22 +0000
        Re: usb3 sticks do not seem to work properly. "Carlos E. R." <robin_listas@es.invalid> - 2019-02-12 21:40 +0100
      Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-11 23:29 -0500
        Re: usb3 sticks do not seem to work properly. Doug Laidlaw <laidlaws@hotkey.net.au> - 2019-02-13 06:40 +1100
          Re: usb3 sticks do not seem to work properly. Doug Laidlaw <laidlaws@hotkey.net.au> - 2019-02-14 03:01 +1100
            Re: usb3 sticks do not seem to work properly. "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-13 23:24 -0500
  Re: usb3 sticks do not seem to work properly. Jasen Betts <jasen@xnet.co.nz> - 2019-02-12 01:50 +0000

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