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Re: Live Fille System Backup

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On 2017-05-09, tomas@tuxteam.de <tomas@tuxteam.de> wrote:
>
> On Mon, May 08, 2017 at 04:03:54PM -0700, Sergei G wrote:
>> And if you think application consistency is nothing to worry about know
>> that Git on Ext4 has failed to recover.
>> 
>> My current conclusion:
>> 
>> 1. If I want application consistency I have to take down any application
>> that has an internal database or backup those applications prior to FS
>> backup.
>
> That depends. There are applications designed with (on-disk) consistency
> in mind (I mention PostgreSQL, I start sounding like a broken record).
>
> But whether you have to "take down" the application or just "alert" it
> for the time the snapshot takes, without its cooperation you either risk
> inconsistent state or bad performance (there are cases where apps chose
> number two, because they aren't designed for high throughput anyway).
>
> The gist is:
>
>   (a) file system magic can't "do" it alone
>   (b) most of the time, a naive "snapshot" with rsync will do
>   (b') you alone can decide, based on your apps & requirements,
>       whether the above "most of the time" works for you
>
> With snapshotting file systems (be it native or assisted) you get just
> faster snapshots, i.e. you mitigate the problem. If you want to go all
> the way, you have to get the app's cooperation, either voluntary (it's
> designed for that) or forced (shutdown)

Because someone mentioned Btrfs and its backup "magic," I'm looking at
the wiki, which says (amongst other things):

https://btrfs.wiki.kernel.org/index.php/Incremental_Backup

 Instant, Atomic COW Snapshots
  Since the snapshots are atomic, when a snapshot is restored it appears to
  applications as if a power loss had occurred (and the filesystem has gone back
  to an earlier state). Thus it is possible to backup databases without stopping
  them beforehand. 

I don't know what an atomic cow is (maybe some poor bovine living near
Chernobyl) but it sounds interesting.

I wonder if Btrfs has any notable drawbacks as a file system.

BTW, I learned (by way of your least favorite search engine) that the inventor
of the Monoyer chart (Ferdinand Monoyer) embedded his name (and occupation--DM,
docteur en médecine) in the chart (beginning on the penultimate line, the last
and first letters read vertically upwards).

These French are clever devils.

> There's no magic.
>
> cheers
> - -- tomás
>    "all generalizations suck"
>
>


-- 
"It might be a vision--of a shell, of a wheelbarrow, of a fairy kingdom on the
far side of the hedge; or it might be the glory of speed; no one knew." --Mrs.
Ramsay, speculating on why her little daughter might be dashing about, in "To
the Lighthouse," by Virginia Woolf.

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Thread

Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-05 01:20 +0200
  Re: Live Fille System Backup Anders Andersson <pipatron@gmail.com> - 2017-05-05 03:50 +0200
    Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-05 06:50 +0200
      Re: Live Fille System Backup Dejan Jocic <jodejka@gmail.com> - 2017-05-05 09:00 +0200
        Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-05 22:40 +0200
          Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-05 23:20 +0200
            Re: Live Fille System Backup Henrique de Moraes Holschuh <hmh@debian.org> - 2017-05-06 00:00 +0200
              Re: Live Fille System Backup conover@rahul.net (John Conover) - 2017-05-06 01:30 +0200
                Re: Live Fille System Backup Henrique de Moraes Holschuh <hmh@debian.org> - 2017-05-06 02:30 +0200
          Re: Live Fille System Backup Henrique de Moraes Holschuh <hmh@debian.org> - 2017-05-06 00:00 +0200
          Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-06 08:00 +0200
            Re: Live Fille System Backup Dan Ritter <dsr@randomstring.org> - 2017-05-06 12:50 +0200
              Re: Live Fille System Backup tomas@tuxteam.de - 2017-05-06 16:00 +0200
                Re: Live Fille System Backup Henrique de Moraes Holschuh <hmh@debian.org> - 2017-05-06 19:20 +0200
                Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-06 21:50 +0200
                Re: Live Fille System Backup Henrique de Moraes Holschuh <hmh@debian.org> - 2017-05-06 23:10 +0200
                Re: Live Fille System Backup Ben Caradoc-Davies <ben@transient.nz> - 2017-05-07 01:00 +0200
                Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-07 12:00 +0200
                Re: Live Fille System Backup rhkramer@gmail.com - 2017-05-07 14:50 +0200
                Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-07 17:00 +0200
                Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-09 00:50 +0200
                Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-09 01:10 +0200
                Re: Live Fille System Backup tomas@tuxteam.de - 2017-05-09 10:00 +0200
                Re: Live Fille System Backup Greg Wooledge <wooledg@eeg.ccf.org> - 2017-05-09 14:10 +0200
                Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-09 14:30 +0200
                Re: Live Fille System Backup Curt <curty@free.fr> - 2017-05-09 15:20 +0200
                Re: Live Fille System Backup Curt <curty@free.fr> - 2017-05-09 14:10 +0200
                Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-09 14:30 +0200
  Re: Live Fille System Backup <tomas@tuxteam.de> - 2017-05-05 09:20 +0200
  Re: Live Fille System Backup Bob Weber <bobrweber@gmail.com> - 2017-05-06 01:00 +0200
  Re: Live Fille System Backup Stefan Monnier <monnier@iro.umontreal.ca> - 2017-05-12 15:00 +0200
    Re: Live Fille System Backup Sergei G <sergeig.public@gmail.com> - 2017-05-25 05:40 +0200

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