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From: pg@btrfs.list.sabi.co.UK (Peter Grandi)
To: Linux fs Btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: number of subvolumes
Date: Wed, 23 Aug 2017 13:11:33 +0100	[thread overview]
Message-ID: <22941.28917.315668.107348@tree.ty.sabi.co.uk> (raw)
In-Reply-To: <20170823071821.GA28319@rus.uni-stuttgart.de>

> This is a vanilla SLES12 installation: [ ... ] Why does SUSE
> ignore this "not too many subvolumes" warning?

As in many cases with Btrfs "it's complicated" because of the
interaction of advanced features among themselves and the chosen
implementation and properties of storage; anisotropy rules.

IIRC the main problem actually is not with "too many subvolumes",
but with too many "reflinks"/"backrefs"; subvolumes, in particular
snapshots, are just the main way to create them:

  https://www.spinics.net/lists/linux-btrfs/msg42808.html

A couple dozen subvolumes without reflinks as in the '/' scheme
used by SUSE are going to be almost always fine.

Then there is different a issue: I remember seeing a post by a SUSE
guy saying that the 10/10/10/10 (hourly/daily/monthly/yearly)
snapshots in the default settings for 'snapper' was a bad idea
because it would create way too many snapshots, but that he was
told to set those defaults that high. I can imagine a cowardly but
plausible reason why "management" would want those defaults.

Some semi-useful links:

* Home page for 'snapper'
  https://snapper.io/
* Announcement of 'snapper'
  https://lizards.opensuse.org/2011/04/01/introducing-snapper/
* Useful maintenance scripts
  https://github.com/kdave/btrfsmaintenance

  parent reply	other threads:[~2017-08-23 12:11 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-22 13:22 netapp-alike snapshots? Ulli Horlacher
2017-08-22 13:44 ` Peter Becker
2017-08-22 14:24   ` Ulli Horlacher
2017-08-22 16:08     ` Peter Becker
2017-08-22 16:48       ` Ulli Horlacher
2017-08-22 16:45     ` Roman Mamedov
2017-08-22 16:57       ` Ulli Horlacher
2017-08-22 17:19         ` A L
2017-08-22 18:01           ` Ulli Horlacher
2017-08-22 18:36             ` Peter Grandi
2017-08-22 20:48               ` Ulli Horlacher
2017-08-23  7:18                 ` number of subvolumes Ulli Horlacher
2017-08-23  8:37                   ` A L
2017-08-23 16:48                     ` Ferry Toth
2017-08-24 17:45                       ` Peter Grandi
2017-08-31  6:49                         ` Ulli Horlacher
2017-08-31 11:18                           ` Austin S. Hemmelgarn
2017-08-31 14:38                             ` Michał Sokołowski
2017-08-31 16:18                               ` Duncan
2017-09-01 10:21                                 ` ein
2017-09-01 11:47                                   ` Austin S. Hemmelgarn
2017-08-24 19:40                       ` Marat Khalili
2017-08-24 21:56                         ` Ferry Toth
2017-08-25  5:54                           ` Chris Murphy
2017-08-25 11:45                           ` Austin S. Hemmelgarn
2017-08-25 12:55                             ` Ferry Toth
2017-08-25 19:18                               ` Austin S. Hemmelgarn
2017-08-23 12:11                   ` Peter Grandi [this message]
2017-08-22 21:53               ` user snapshots Ulli Horlacher
2017-08-23  6:28                 ` Dmitrii Tcvetkov
2017-08-23  7:16                   ` Dmitrii Tcvetkov
2017-08-23  7:20                     ` Ulli Horlacher
2017-08-23 11:42                       ` Peter Grandi
2017-08-23 21:13                         ` Ulli Horlacher
2017-08-25 11:28                           ` Austin S. Hemmelgarn
2017-08-22 17:36         ` netapp-alike snapshots? Roman Mamedov
2017-08-22 18:10           ` Ulli Horlacher
2017-09-09 13:26 ` Ulli Horlacher
2017-09-09 13:36   ` Marc MERLIN
2017-09-09 13:44     ` Ulli Horlacher
2017-09-09 19:43       ` Andrei Borzenkov
2017-09-09 19:52         ` Ulli Horlacher
2017-09-10  7:10           ` A L
2017-09-10 14:54         ` Marc MERLIN

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