Re: OT: minimum bs for dd?

From	<tomas@tuxteam.de>
Newsgroups	linux.debian.user
Subject	Re: OT: minimum bs for dd?
Date	2021-05-17 15:00 +0200
Message-ID	<CfL0K-6W5-3@gated-at.bofh.it> (permalink)
References	(5 earlier) <CfEBX-3mC-1@gated-at.bofh.it> <CfF50-3vP-7@gated-at.bofh.it> <CfFRn-40O-1@gated-at.bofh.it> <CfGu5-4sx-5@gated-at.bofh.it> <CfKxI-6ML-7@gated-at.bofh.it>
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On Mon, May 17, 2021 at 03:21:20PM +0300, Andrei POPESCU wrote:

[...]

> If my understanding from your quotes and David's links is correct 
> oflag=sync may be slower in specific circumstances, but it depends on so 
> many factors (hardware, caches, block size used, etc.) that it is hard 
> to predict.

The proof would be in the pudding, of course.

> Quite likely it won't make a significant difference for "regular" use.

For regular use, the oflag is (as I tried to explain) invaluable to me.

See, I bought myself a refurbished notebook, but I didn't skimp on
RAM: 16GB.

My main dd use is to write some image onto a flash removable (stick,
SD card). The write channel is slow, the available buffer big.

Once the write is done (if I do cp or forget the sync), not much
is actually written to the drive. Then I say "sync", and... the
sync goes shopping, without telling me when it plans to be back :-)

With "oflags=sync status=progress" (or by sending SIGHUP to the
dd process) I can get a rough idea when I'll be able to pull out
that stick.

Needless to say, I don't mind the copy being some, say, 10% slower
(totally making that up, but for a seq writing with some biggish
block size, I'd expect even that to be an outrageous exaggeration).

Cheers
 - t

Thread

OT: minimum bs for dd? Bob Bernstein <poobah@ruptured-duck.com> - 2021-05-15 22:30 +0200
  Re: OT: minimum bs for dd? The Wanderer <wanderer@fastmail.fm> - 2021-05-15 22:40 +0200
  Re: OT: minimum bs for dd? IL Ka <kazakevichilya@gmail.com> - 2021-05-15 22:40 +0200
    Re: OT: minimum bs for dd? Bob Bernstein <bob@fanatick.org> - 2021-05-16 09:40 +0200
    Re: OT: minimum bs for dd? Michael Stone <mstone@debian.org> - 2021-05-16 19:50 +0200
      Re: OT: minimum bs for dd? Richard Owlett <rowlett@cloud85.net> - 2021-05-16 20:40 +0200
        Re: OT: minimum bs for dd? Stefan Monnier <monnier@iro.umontreal.ca> - 2021-05-17 00:40 +0200
          Re: OT: minimum bs for dd? The Wanderer <wanderer@fastmail.fm> - 2021-05-17 00:50 +0200
            Re: OT: minimum bs for dd? "Thomas Schmitt" <scdbackup@gmx.net> - 2021-05-17 09:00 +0200
              Re: OT: minimum bs for dd? The Wanderer <wanderer@fastmail.fm> - 2021-05-17 12:30 +0200
            Re: OT: minimum bs for dd? Greg Wooledge <greg@wooledge.org> - 2021-05-17 13:20 +0200
          Re: OT: minimum bs for dd? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-05-17 08:10 +0200
            Re: OT: minimum bs for dd? <tomas@tuxteam.de> - 2021-05-17 08:40 +0200
              Re: OT: minimum bs for dd? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-05-17 09:30 +0200
                Re: OT: minimum bs for dd? David <bouncingcats@gmail.com> - 2021-05-17 10:00 +0200
                Re: OT: minimum bs for dd? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-05-17 14:10 +0200
                Re: OT: minimum bs for dd? <tomas@tuxteam.de> - 2021-05-17 10:10 +0200
                Re: OT: minimum bs for dd? Andrei POPESCU <andreimpopescu@gmail.com> - 2021-05-17 14:30 +0200
                Re: OT: minimum bs for dd? <tomas@tuxteam.de> - 2021-05-17 15:00 +0200
                info pages WHERE? -- was [Re: OT: minimum bs for dd?] Richard Owlett <rowlett@cloud85.net> - 2021-05-17 15:00 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] <tomas@tuxteam.de> - 2021-05-17 15:10 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Richard Owlett <rowlett@cloud85.net> - 2021-05-17 15:20 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] IL Ka <kazakevichilya@gmail.com> - 2021-05-17 15:30 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Richard Owlett <rowlett@cloud85.net> - 2021-05-17 16:00 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Greg Wooledge <greg@wooledge.org> - 2021-05-17 15:40 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] "Thomas Schmitt" <scdbackup@gmx.net> - 2021-05-17 16:10 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Greg Wooledge <greg@wooledge.org> - 2021-05-17 17:10 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] "Thomas Schmitt" <scdbackup@gmx.net> - 2021-05-17 18:00 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Brian <ad44@cityscape.co.uk> - 2021-05-17 20:30 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Greg Wooledge <greg@wooledge.org> - 2021-05-17 20:50 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] Brian <ad44@cityscape.co.uk> - 2021-05-17 21:00 +0200
                Re: info pages WHERE? -- was [Re: OT: minimum bs for dd?] <tomas@tuxteam.de> - 2021-05-17 16:10 +0200
            Re: OT: minimum bs for dd? Brian <ad44@cityscape.co.uk> - 2021-05-17 16:20 +0200
          Re: OT: minimum bs for dd? <tomas@tuxteam.de> - 2021-05-17 08:40 +0200
            Re: OT: minimum bs for dd? Richard Hector <richard@walnut.gen.nz> - 2021-05-17 13:40 +0200
        Re: OT: minimum bs for dd? Michael Stone <mstone@debian.org> - 2021-05-16 20:50 +0200
          Re: OT: minimum bs for dd? "Andrew M.A. Cater" <amacater@einval.com> - 2021-05-16 23:40 +0200

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