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Re: recommendations for supported, affordable hardware raid controller.

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>> AIUI a journaling filesystem provides a two-step process to achieve atomic
>> writes of multiple sectors to disk -- e.g. a process wants to put some data
>> into a block here (say, a file), a block there (say, a directory), etc., and
>> consistency of the on-disk data structures must be preserved.  The journal
>> provides a two-step process whereby everything is written to the journal,
>> then everything is written to disk.
> That would mean all data is written to the disk twice and would make a
> journaling file system twice as slow compared to a non-journaling file
> system; the journal is typically on the same storage.

On rotating storage, it's definitely not that bad, since typically every
file modification will involve several parts of the disk (at least the
actual data and the inode, and often more), so the log only adds one
head movement to the 2 or 3 already needed.  Furthermore, once it's
written to the log, there is no hurry to do the other writes, so they
can be delayed and coalesced with other nearby writes, reducing head
movement yet further.

So, all in all, the performance impact can be quite varied and will
heavily depend on your use case (and on how much work went into tuning
the filesystem and journaling code).


        Stefan

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recommendations for supported, affordable hardware raid controller. Steven Mainor <steve@degga.net> - 2021-01-01 19:10 +0100
  Re: recommendations for supported, affordable hardware raid  controller. "Alexander V. Makartsev" <avbetev@gmail.com> - 2021-01-01 20:00 +0100
  Re: recommendations for supported, affordable hardware raid  controller. Dan Ritter <dsr@randomstring.org> - 2021-01-01 20:00 +0100
    Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-01 20:40 +0100
  Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-01 21:10 +0100
    Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:30 +0100
      Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:50 +0100
  Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-01 21:20 +0100
  Re: recommendations for supported, affordable hardware raid  controller. Steven Mainor <steve@degga.net> - 2021-01-02 09:20 +0100
    Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-02 10:50 +0100
      Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-02 12:30 +0100
        Re: recommendations for supported, affordable hardware raid  controller. Richard Hector <richard@walnut.gen.nz> - 2021-01-02 17:10 +0100
          Re: recommendations for supported, affordable hardware raid controller. Gene Heskett <gheskett@shentel.net> - 2021-01-02 17:50 +0100
        Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-02 22:40 +0100
          Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-03 10:30 +0100
            Re: recommendations for supported, affordable hardware raid  controller. David Christensen <dpchrist@holgerdanske.com> - 2021-01-03 22:50 +0100
              Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-04 08:30 +0100
            Re: recommendations for supported, affordable hardware raid controller. Stefan Monnier <monnier@iro.umontreal.ca> - 2021-01-03 23:20 +0100
            Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-04 02:00 +0100
              Re: recommendations for supported, affordable hardware raid  controller. Andrei POPESCU <andreimpopescu@gmail.com> - 2021-01-04 08:40 +0100
                Re: recommendations for supported, affordable hardware raid  controller. Michael Stone <mstone@debian.org> - 2021-01-04 14:40 +0100
    Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-02 12:50 +0100
      Re: recommendations for supported, affordable hardware raid controller. Nicholas Geovanis <nickgeovanis@gmail.com> - 2021-01-02 16:30 +0100
        Re: recommendations for supported, affordable hardware raid controller. Sven Hartge <sven@svenhartge.de> - 2021-01-02 17:30 +0100
        Re: recommendations for supported, affordable hardware raid  controller. Alain D D Williams <addw@phcomp.co.uk> - 2021-01-02 18:40 +0100
  Re: recommendations for supported, affordable hardware raid controller. deloptes <deloptes@gmail.com> - 2021-01-02 10:00 +0100

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