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Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes

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David Wright <deblis@lionunicorn.co.uk> writes:

> On Tue 10 Sep 2024 at 11:56:25 (+0300), Anssi Saari wrote:

>> Why do you think that? Which part of the fsync manpage explicitly covers
>> fsync's effect on device files? Share share, it's fair.

>  “fsync() transfers ("flushes") all modified in-core data of (i.e.,
>   modified buffer cache pages for) the file referred to by the file
>   descriptor fd to the disk device (or other permanent storage device)
>   so that all changed information can be retrieved even after the
>   system crashed or was rebooted. This includes writing through or
>   flushing a disk cache if present. The call blocks until the device
>   reports that the transfer has completed. It also flushes metadata
>   information associated with the file (see stat(2)).”

You just parroted a man page I had already read. Why did you think
that'd be helpful? I asked the questions because the man page didn't
answer my questions. As you are apparemntly unable I found for example
https://unix.stackexchange.com/questions/473854/block-device-cache-v-s-a-filesystem
and so arrived to the conclusion that the final close(2) call on a block
device already flushes all buffers before returning. So the answer to
the question "is running sync needed after dd to block device" is
no. Someone else posted that too on this list recently, in another
thread.

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Disk drive zero-fill benchmarks for various synchronization methods  and block sizes David Christensen <dpchrist@holgerdanske.com> - 2024-09-08 20:10 +0200
  Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-09 11:00 +0200
    Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes David Wright <deblis@lionunicorn.co.uk> - 2024-09-09 15:40 +0200
      Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-10 11:00 +0200
        Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-13 14:10 +0200
          Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes <tomas@tuxteam.de> - 2024-09-13 20:40 +0200
            Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes Michael Stone <mstone@debian.org> - 2024-09-16 04:50 +0200
              Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes <tomas@tuxteam.de> - 2024-09-16 06:40 +0200
          Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes Jeffrey Walton <noloader@gmail.com> - 2024-09-13 21:10 +0200
            Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes David Christensen <dpchrist@holgerdanske.com> - 2024-09-14 01:40 +0200
            Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-16 11:10 +0200
              Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes <tomas@tuxteam.de> - 2024-09-16 11:20 +0200
                Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-16 12:50 +0200
                Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes <tomas@tuxteam.de> - 2024-09-16 13:00 +0200
                Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes Michael Stone <mstone@debian.org> - 2024-09-16 13:20 +0200
          Re: Disk drive zero-fill benchmarks for various synchronization methods and  block sizes "Rick Thomas" <rick.thomas@pobox.com> - 2024-09-13 23:20 +0200
          Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes David Wright <deblis@lionunicorn.co.uk> - 2024-09-16 21:20 +0200
  Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes Michael Stone <mstone@debian.org> - 2024-09-16 05:00 +0200
    Re: Disk drive zero-fill benchmarks for various synchronization methods and block sizes Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2024-09-16 12:20 +0200
      Re: Disk drive zero-fill benchmarks for various synchronization  methods and block sizes Michael Stone <mstone@debian.org> - 2024-09-16 13:40 +0200

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