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Bug#840248: debian-installer: Add btrfs subvolume setting for snapshot

package: debian-installer
severity: wishlist

 It's enhancement proposal, not bug report. Now Debian system cannot use
 whole btrfs power, but we can improve it.

 debian-installer can format disk with btrfs now, but it is NOT appropriate
 setting with btrfs. We can just format partion with btrfs but cannot create
 btrfs "subvolume" at that time.

 Subvolume is a bit special idea, you can slice one btrfs partion to some 
 subvolume and can set quota for each subvolume, also mount directory and
 get snapshot for each.

 So, I'll propose debian-installer to add btrfs subvolume setting menu or
 add subvolume setting like SUSE by default.

 For detail, see Btrfs Wiki page

 Well, for exapmle, openSUSE's installer (YaST2?) creates defalut partition
 as btrfs and below subvolumes by default.
@/var/lib/libvirt/images (option "no copy on write")
@/var/lib/mariadb (option "no copy on write")
@/var/lib/mysql (option "no copy on write")
@/var/lib/pgsql (option "no copy on write")

 and default / subvolume.

 - Snapshotting is targeted to default / subvolume and whole system except
   above subvolumes. Separating some directories are very important for btrfs
   snapshot. It makes easy to rollback to previous snapshot image without any
   losing data.
 - And, "no copy on write" mount option is important for DB systems 
   for performance.

 - I'm not sure why they separate /boot/grub2/i386-pc and x86_64-efi

 If it is hard to add creating subvolume menu, just follow SUSE's decision
 is worse.

 Some people says "btrfs is not stable", but SUSE and Oracle support it as
 commercial support. Some features like RAID5,6 is not stable as it says(*),
 but upstream developer Chris Mason says "Aging" state in Facebook(*). So
 it's worse to treat btrfs as sane choice and release its power as possible,

 *) https://btrfs.wiki.kernel.org/index.php/Status
 *) https://youtu.be/W3QRWUfBua8?t=17m51s


 Hideki Yamane     henrich @ debian.or.jp/org

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