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Re: DD bs=4M option on USB mem-stick creates false format

From David Christensen <dpchrist@holgerdanske.com>
Newsgroups linux.debian.user
Subject Re: DD bs=4M option on USB mem-stick creates false format
Date 2017-03-27 20:20 +0200
Message-ID <tpHpf-3Jt-11@gated-at.bofh.it> (permalink)
References <tpkiZ-3bf-3@gated-at.bofh.it> <tpu8F-252-5@gated-at.bofh.it> <tpBDb-7On-9@gated-at.bofh.it> <tpC6e-83W-13@gated-at.bofh.it>
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On 03/27/2017 05:38 AM, Greg Wooledge wrote:
> ... the bs= option in dd.  All that does is make the dd command run a
> tiny bit faster or slower.

As I understand it, writes smaller than a flash page size cause the 
flash drive firmware to fetch or erase an available page of flash, 
combine the unmodified bytes from the existing page with the new bytes, 
and then burn the page (and internal meta-data).  So, if flash pages are 
8K, burning in 512 blocks could cause 16 such operations, taking longer 
and eating up the life of your flash cells.  That said, RAM buffering by 
the operating system, RAM buffering by the USB flash drive, and firmware 
that anticipates serial writes should mitigate these effects.


For example, here is an ADATA 4 marketing-GB USB flash drive:

2017-03-27 10:50:16 root@jesse ~
# dmesg | tail -n 17
[ 2794.868073] usb 3-3: new high-speed USB device number 3 using ehci-pci
[ 2795.003837] usb 3-3: New USB device found, idVendor=125f, idProduct=c08a
[ 2795.003845] usb 3-3: New USB device strings: Mfr=1, Product=2, 
SerialNumber=3
[ 2795.003851] usb 3-3: Product: ADATA USB Flash Drive
[ 2795.003856] usb 3-3: Manufacturer: ADATA
[ 2795.003861] usb 3-3: SerialNumber: 1392303332110024
[ 2795.026206] usb-storage 3-3:1.0: USB Mass Storage device detected
[ 2795.026718] scsi2 : usb-storage 3-3:1.0
[ 2795.026845] usbcore: registered new interface driver usb-storage
[ 2796.025404] scsi 2:0:0:0: Direct-Access     ADATA    USB Flash Drive 
0.00 PQ: 0 ANSI: 4
[ 2796.027040] sd 2:0:0:0: Attached scsi generic sg2 type 0
[ 2796.028370] sd 2:0:0:0: [sdb] 7592960 512-byte logical blocks: (3.88 
GB/3.62 GiB)
[ 2796.031242] sd 2:0:0:0: [sdb] Write Protect is off
[ 2796.031251] sd 2:0:0:0: [sdb] Mode Sense: 23 00 00 00
[ 2796.032626] sd 2:0:0:0: [sdb] Write cache: disabled, read cache: 
enabled, doesn't support DPO or FUA
[ 2796.041663]  sdb: sdb1 sdb2
[ 2796.072615] sd 2:0:0:0: [sdb] Attached SCSI removable disk


Burning 10 MB using 'bs=1M':

2017-03-27 11:01:23 root@jesse ~
# time dd if=/dev/urandom of=/dev/sdb seek=3000 count=10 bs=1M && sync
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 2.93679 s, 3.6 MB/s

real	0m2.941s
user	0m0.000s
sys	0m1.020s


Burning 10 MB using default bs:

2017-03-27 11:01:57 root@jesse ~
# time dd if=/dev/urandom of=/dev/sdb seek=6144000 count=20480 && sync
20480+0 records in
20480+0 records out
10485760 bytes (10 MB) copied, 5.38085 s, 1.9 MB/s

real	0m5.385s
user	0m0.012s
sys	0m1.388s


David

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Thread

DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-26 19:40 +0200
  Re: DD bs=4M option on USB mem-stick creates false format Darac Marjal <mailinglist@darac.org.uk> - 2017-03-26 19:50 +0200
  Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-26 20:00 +0200
  Re: DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-26 20:10 +0200
  Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-26 20:20 +0200
    Re: DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-27 12:20 +0200
      Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-27 14:20 +0200
        Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-27 14:40 +0200
          Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-28 12:20 +0200
            Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-28 14:00 +0200
              Re: DD bs=4M option on USB mem-stick creates false format <tomas@tuxteam.de> - 2017-03-28 14:20 +0200
                Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-28 15:50 +0200
                Re: DD bs=4M option on USB mem-stick creates false format <tomas@tuxteam.de> - 2017-03-28 15:50 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-28 16:30 +0200
                Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-28 17:40 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-28 19:10 +0200
              Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-28 14:20 +0200
                Re: DD bs=4M option on USB mem-stick creates false format <tomas@tuxteam.de> - 2017-03-28 14:20 +0200
                Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-28 14:40 +0200
                Re: DD bs=4M option on USB mem-stick creates false format Richard Owlett <rowlett@cloud85.net> - 2017-03-28 15:20 +0200
            Re: DD bs=4M option on USB mem-stick creates false format songbird <songbird@anthive.com> - 2017-03-28 19:30 +0200
              Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-28 20:40 +0200
                Re: DD bs=4M option on USB mem-stick creates false format songbird <songbird@anthive.com> - 2017-03-29 07:50 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-29 10:30 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-29 12:20 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-29 12:40 +0200
            Re: DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-29 00:50 +0200
              Re: DD bs=4M option on USB mem-stick creates false format songbird <songbird@anthive.com> - 2017-03-29 07:50 +0200
              Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-29 10:20 +0200
                Re: DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-29 22:30 +0200
                Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-30 00:00 +0200
              Re: DD bs=4M option on USB mem-stick creates false format Curt <curty@free.fr> - 2017-03-29 16:40 +0200
                Re:Movie 'n Book recommendations by Curt kAt <giathnygeia@openmailbox.org> - 2017-03-29 22:10 +0200
                Re: Movie 'n Book recommendations by Curt Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-29 23:40 +0200
                Re: Movie 'n Book recommendations by Curt kAt <giathnygeia@openmailbox.org> - 2017-03-30 20:10 +0200
                Re: Movie 'n Book recommendations by Curt Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-30 20:20 +0200
                Re: Movie 'n Book recommendations by Curt Richard Owlett <rowlett@cloud85.net> - 2017-03-30 20:50 +0200
                Re: Movie 'n Book recommendations by Curt Catherine Gramze <rhiamom@mac.com> - 2017-03-30 20:30 +0200
                Re: Movie 'n Book recommendations by Curt Eike Lantzsch <zp6cge@gmx.net> - 2017-03-30 20:40 +0200
                Re: Movie 'n Book recommendations by Curt John Hasler <jhasler@newsguy.com> - 2017-03-30 21:30 +0200
                Re: Movie 'n Book recommendations by Curt Terence <terence.john@gmail.com> - 2017-03-30 22:00 +0200
                Re: Movie 'n Book recommendations by Curt Catherine Gramze <rhiamom@mac.com> - 2017-03-30 22:40 +0200
                Re: Movie 'n Book recommendations by Curt Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-31 00:20 +0200
                Re: Movie 'n Book recommendations by Curt Catherine Gramze <rhiamom@mac.com> - 2017-03-31 01:30 +0200
                Re: Movie 'n Book recommendations by Curt Jonathan Dowland <jmtd@debian.org> - 2017-03-31 09:50 +0200
                Re: Movie 'n Book recommendations by Curt Terence <terence.john@gmail.com> - 2017-03-31 12:40 +0200
                OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) rhkramer@gmail.com - 2017-03-31 15:10 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-31 15:40 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) Greg Wooledge <wooledg@eeg.ccf.org> - 2017-03-31 15:50 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) rhkramer@gmail.com - 2017-03-31 16:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) Eike Lantzsch <zp6cge@gmx.net> - 2017-03-31 16:30 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re:  Movie 'n Book recommendations by Curt) Curt <curty@free.fr> - 2017-03-31 18:00 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) kAt <giathnygeia@openmailbox.org> - 2017-04-01 00:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) rhkramer@gmail.com - 2017-03-31 16:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-31 17:00 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re:  Movie 'n Book recommendations by Curt) Liam O'Toole <liam.p.otoole@gmail.com> - 2017-04-01 19:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re: Movie 'n Book recommendations by Curt) Lisi Reisz <lisi.reisz@gmail.com> - 2017-04-01 20:10 +0200
                Re: OT: speaking of days (weeks, months, years, etc.)  (was: Re:  Movie 'n Book recommendations by Curt) Liam O'Toole <liam.p.otoole@gmail.com> - 2017-04-01 21:30 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) Peter Hillier-Brook <phb@hbsys.plus.com> - 2017-03-31 17:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) kAt <giathnygeia@openmailbox.org> - 2017-04-01 00:20 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) Lisi Reisz <lisi.reisz@gmail.com> - 2017-04-01 00:50 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) GiaThnYgeia <GiaThnYgeia@openmailbox.org> - 2017-04-01 18:10 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) Stefan Monnier <monnier@iro.umontreal.ca> - 2017-03-31 16:50 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) Lisi Reisz <lisi.reisz@gmail.com> - 2017-03-31 17:00 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) Eike Lantzsch <zp6cge@gmx.net> - 2017-03-31 17:10 +0200
                Re: OT: speaking of days (weeks, months, years, etc.) kAt <giathnygeia@openmailbox.org> - 2017-04-01 00:40 +0200
        Re: DD bs=4M option on USB mem-stick creates false format Pascal Hambourg <pascal@plouf.fr.eu.org> - 2017-03-27 21:00 +0200
          Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-27 21:50 +0200
  Re: DD bs=4M option on USB mem-stick creates false format David Christensen <dpchrist@holgerdanske.com> - 2017-03-27 06:10 +0200
    Re: DD bs=4M option on USB mem-stick creates false format kAt <giathnygeia@openmailbox.org> - 2017-03-27 14:10 +0200
      Re: DD bs=4M option on USB mem-stick creates false format rhkramer@gmail.com - 2017-03-27 14:30 +0200
      Re: DD bs=4M option on USB mem-stick creates false format Greg Wooledge <wooledg@eeg.ccf.org> - 2017-03-27 14:40 +0200
        Re: DD bs=4M option on USB mem-stick creates false format "Thomas Schmitt" <scdbackup@gmx.net> - 2017-03-27 15:10 +0200
        Re: DD bs=4M option on USB mem-stick creates false format David Christensen <dpchrist@holgerdanske.com> - 2017-03-27 20:20 +0200
          Re: DD bs=4M option on USB mem-stick creates false format Pascal Hambourg <pascal@plouf.fr.eu.org> - 2017-03-28 00:00 +0200
      Re: DD bs=4M option on USB mem-stick creates false format David Christensen <dpchrist@holgerdanske.com> - 2017-03-27 19:40 +0200

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