From: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
To: Andrei Borzenkov <arvidjaar@gmail.com>, ST <smntov@gmail.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Several questions regarding btrfs
Date: Wed, 1 Nov 2017 14:28:12 -0400 [thread overview]
Message-ID: <708f17c4-c6e6-78f1-06f4-e3bda6ea208c@gmail.com> (raw)
In-Reply-To: <deeb56f6-1245-abfd-bfdb-ab399bc857b8@gmail.com>
On 2017-11-01 13:52, Andrei Borzenkov wrote:
> 01.11.2017 15:01, Austin S. Hemmelgarn пишет:
> ...
>> The default subvolume is what gets mounted if you don't specify a
>> subvolume to mount. On a newly created filesystem, it's subvolume ID 5,
>> which is the top-level of the filesystem itself. Debian does not
>> specify a subvo9lume in /etc/fstab during the installation, so setting
>> the default subvolume will control what gets mounted. If you were to
>> add a 'subvolume=' or 'subvolid=' mount option to /etc/fstab for that
>> filesystem, that would override the default subvolume.
>>
>> The reason I say to set the default subvolume instead of editing
>> /etc/fstab is a pretty simple one though. If you edit /etc/fstab and
>> don't set the default subvolume, you will need to mess around with the
>> bootloader configuration (and possibly rebuild the initramfs) to make
>> the system bootable again, whereas by setting the default subvolume, the
>> system will just boot as-is without needing any other configuration
>> changes.
>
> That breaks as soon as you have nested subvolumes that are not
> explicitly mounted because they are lost in new snapshot.
>
Unless they have been created manually, there won't be any such
subvolumes on a Debian system. Debian treats BTRFS no different from
any other filesystem during the install, so you get no subvolumes
whatsoever (in contrast to Fedora and SUSE treating BTRFS as a volume
manager and not a filesystem, and thus having subvolumes all over the
place in a default install).
Regardless of if you update /etc/fstab to point to the new subvolume or
not, any old ones need to be either copied (the preferred method for
stuff that isn't supposed to be equivalent to a separate filesystem), or
have entries put in /etc/fstab.
next prev parent reply other threads:[~2017-11-01 18:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 16:23 Several questions regarding btrfs ST
2017-10-31 17:45 ` Austin S. Hemmelgarn
2017-10-31 18:51 ` Andrei Borzenkov
2017-10-31 19:07 ` Austin S. Hemmelgarn
2017-10-31 20:06 ` ST
2017-11-01 12:01 ` Austin S. Hemmelgarn
2017-11-01 14:05 ` ST
2017-11-01 15:31 ` Lukas Pirl
2017-11-01 17:20 ` Austin S. Hemmelgarn
2017-11-02 9:09 ` ST
2017-11-02 11:01 ` Austin S. Hemmelgarn
2017-11-02 15:59 ` ST
[not found] ` <E7316F3D-708C-4D5E-AB4B-F54B0B8471C1@rqc.ru>
2017-11-02 16:28 ` ST
2017-11-02 17:13 ` Austin S. Hemmelgarn
2017-11-02 17:32 ` Andrei Borzenkov
2017-11-01 17:52 ` Andrei Borzenkov
2017-11-01 18:28 ` Austin S. Hemmelgarn [this message]
2017-11-01 12:15 ` Duncan
2017-10-31 16:29 ST
2017-11-06 21:48 ` waxhead
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