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From: David Alcorn <nroclaed@gmail.com>
To: linux-btrfs@vger.kernel.org
Subject: Install to or Recover RAID Array Subvolume Root?
Date: Mon, 18 Apr 2016 13:22:34 +0800	[thread overview]
Message-ID: <CALq5X_gB0YkRMZx7Af+gAYdYRhojiKSCV9r3g8YPG6_8YR+9DQ@mail.gmail.com> (raw)

Debian's default installer (1) can not create a BTRFS raid array
during installation, and (2) installs to the default subvol of the
BTRFS target.  The default subvol is 5 (BTRFS root) unless (i) prior
to installation a BTRFS file-system was created, (ii) the default
subvol is set to something other than 5, and (iii) you do not format
the installation target during install. This perspective benefits from
https://aykevl.nl/2015/11/debian-btrfs-subvolume.

Can Debian install BTRFS to a pre-existing BTRFS RAID 6 array?  If the
array's default is set to ,say subvolid 257, can I install to array
subvolume 257?  The goal is to install to a subvolume on the array
without disturbing date on other array subvolumes.

I erred and shutdown my NAS during a balance.  Grub lost track of my
root.  Root was on RAID 6 array subvolid 257.  I can boot a different
root from a USB flash drive but neither update-grub not install-grub
sees my old root on array subvolid 257.  I am happy to either recover
or lose array subvolid 257 but do not want to lose data on other array
subvol's.  I prefer to have my root on the array rather than a flash
drive.  The balance completed successfully after I booted from the
flash drive.

I am running a debian back-ported 4.4.0 kernel with btrfs-progs v4.4
on both my flash drive and array subvolid 257.  Both installs are
UEFI.  df -h reports:

Filesystem      Size  Used Avail Use% Mounted on
udev             10M     0   10M   0% /dev
tmpfs           790M  8.6M  781M   2% /run
/dev/sdb3       3.8G  1.1G  2.4G  31% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/sdb1        93M  311K   93M   1% /boot/efi
/dev/sde         22T  4.9T   13T  29% /lit

             reply	other threads:[~2016-04-18  5:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-18  5:22 David Alcorn [this message]
2016-04-18 12:31 ` Install to or Recover RAID Array Subvolume Root? Austin S. Hemmelgarn
2016-04-18 15:12   ` Chris Murphy
2016-04-18 15:15     ` Austin S. Hemmelgarn
2016-04-18 15:39       ` Chris Murphy
2016-04-18 15:52         ` Austin S. Hemmelgarn
2016-04-18 16:18           ` Chris Murphy
2016-04-18 20:34           ` Nicholas D Steeves
2016-04-19 11:14             ` Austin S. Hemmelgarn
2016-04-19 21:43               ` Nicholas D Steeves
2016-04-18 20:42 ` Nicholas D Steeves
2016-04-19  3:06   ` David Alcorn
2016-04-19 20:53     ` Nicholas D Steeves
2016-04-22 10:44   ` David Alcorn
2016-04-25 19:38     ` Nicholas D Steeves
2016-04-26  9:23       ` David Alcorn
2016-04-27 12:03         ` Nicholas D Steeves

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