Re: Whole Disk Encryption + SSD

From	David Christensen <dpchrist@holgerdanske.com>
Newsgroups	linux.debian.user
Subject	Re: Whole Disk Encryption + SSD
Date	2021-07-02 05:50 +0200
Message-ID	<CwilH-7y5-1@gated-at.bofh.it> (permalink)
References	<Cv0TT-1C0-3@gated-at.bofh.it> <Cv6cV-4QX-1@gated-at.bofh.it> <Cwhzj-715-1@gated-at.bofh.it>
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On 7/1/21 7:55 PM, David Wright wrote:
> On Mon 28 Jun 2021 at 13:36:35 (-0700), David Christensen wrote:
> 
>> I do not set the 'discard' (trim) option in fstab(5).  If and when I
>> want to erase unused blocks (such as before taking an image), I use
>> fstrim(8).
> 
> Can you elaborate on a couple of things:
> 
> How do you "take an image". Is this equivalent to a conventional
> dd if=/dev/sda …, or to some other process?

I wrote a script.  To "take an image", the script invokes dd(1) and 
pipes the output to gzip(1), copying raw device octets to a file.  To 
"restore an image", the process is reversed.


> When I copy an entire conventional drive or partition, all the
> free blocks/unused sectors are carefully transferred to the copy.

Same here.


> What improvement does erasing unused blocks achieve?

Zero blocks are readily compressed, reducing the size of the image file.


David

Thread

Whole Disk Encryption + SSD piorunz <piorunz@gmx.com> - 2021-06-28 17:00 +0200
  Re: Whole Disk Encryption + SSD Jochen Spieker <ml@well-adjusted.de> - 2021-06-28 18:00 +0200
  Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-28 22:40 +0200
    Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-29 00:00 +0200
    Re: Whole Disk Encryption + SSD Stefan Monnier <monnier@iro.umontreal.ca> - 2021-06-29 02:00 +0200
      Re: Whole Disk Encryption + SSD <tomas@tuxteam.de> - 2021-06-29 09:50 +0200
        Re: Whole Disk Encryption + SSD Stefan Monnier <monnier@iro.umontreal.ca> - 2021-06-30 00:50 +0200
        Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-30 01:00 +0200
    Re: Whole Disk Encryption + SSD Jonathan Dowland <jon+debian-user@dow.land> - 2021-06-29 11:30 +0200
    Re: Whole Disk Encryption + SSD piorunz <piorunz@gmx.com> - 2021-06-29 14:10 +0200
      Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-30 02:20 +0200
    Re: Whole Disk Encryption + SSD David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 05:00 +0200
      Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 05:50 +0200
        Useless use of "dd" Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 07:50 +0200
          Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 09:50 +0200
            Re: Useful use of dd [was: Useless use of "dd"] Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 12:30 +0200
              Re: Useful use of dd "Thomas Schmitt" <scdbackup@gmx.net> - 2021-07-02 13:00 +0200
                Re: Useful use of dd <tomas@tuxteam.de> - 2021-07-02 13:20 +0200
                Re: Useful use of dd Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 13:30 +0200
                Re: Useful use of dd David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:50 +0200
              Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 13:20 +0200
              Re: Useful use of dd Michael Stone <mstone@debian.org> - 2021-07-02 14:50 +0200
              Re: Useful use of dd [was: Useless use of "dd"] Kushal Kumaran <kushal@locationd.net> - 2021-07-02 21:10 +0200
                Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:40 +0200
                Re: Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-03 00:00 +0200
                Re: Creation of empty files [was: Useful use of dd] Michael Stone <mstone@debian.org> - 2021-07-03 15:50 +0200
                Re: Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-03 23:40 +0200
                Re: Creation of empty files [was: Useful use of dd] Michael Stone <mstone@debian.org> - 2021-07-04 06:00 +0200
            Re: Useful use of dd [was: Useless use of "dd"] Greg Wooledge <greg@wooledge.org> - 2021-07-02 13:40 +0200
              Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 13:40 +0200
                Re: Useful use of dd [was: Useless use of "dd"] David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 17:10 +0200
                Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 17:40 +0200
                Re: Useful use of dd [was: Useless use of "dd"] Gunnar Gervin <dofeelok@gmail.com> - 2021-07-03 09:20 +0200
                Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-03 09:30 +0200
            Useless use of shell pipelines [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:40 +0200
              Re: Useless use of shell pipelines [was: Useful use of dd] l0f4r0@tuta.io - 2021-07-03 10:30 +0200
                Re: Useless use of shell pipelines [was: Useful use of dd] Greg Wooledge <greg@wooledge.org> - 2021-07-03 15:40 +0200
          Re: Useless use of "dd" David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 21:40 +0200
        Re: Whole Disk Encryption + SSD David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 17:10 +0200
          Re: Whole Disk Encryption + SSD Michael Stone <mstone@debian.org> - 2021-07-02 17:30 +0200
          Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 20:40 +0200

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