On Freitag, 10. Juni 2016 00:04:04 CEST Ben Hutchings wrote: > On Thu, 2016-06-09 at 18:24 +0200, Martin Steigerwald wrote: […] > > With todays Debian Sid/Experimental on my laptop this still doesn´t work > > right, I still have to add something like – I just recognized after I > > reinstalled initramfs-tools in a crude way after having messed it up by > > accidentally delete /var/lib/initramfs-tools (and then recognizing that it > > may > > have been easier to recover it than what I did): > [...] > > > So whatever local-premount/btrfs does it not sufficient for the BTRFS RAID > > on two LVs case. > > Indeed. As explained in #565676, lvm2 only activates the VGs > containing the root, /usr and hibernate/resume devices (and only if it > can recognise that they are on LVM). Apparently it is not generally > safe to activate all visible VGs. But perhaps that behaviour should be > available as an *option*. That is safe for most systems and I think it > would resolve all the issues blocking this.
Well, it would definately work on my system. > (I don't really understand the purpose of running btrfs on LVM, though. > btrfs integrates logical volume management and I was under the > impression that that's the main reason to use it. If you still need > another layer underneath then why use it at all?) The reason is simple: I want to have the option to use and test different filesystems for my Linux Performance Analysis and Tuning courses and other reasons. Also I have two BTRFS RAID 1, the debian system itself aka /, and home separately, and one data partition only residing on one SSD. Once BTRFS allows different RAID levels in each subvolume it would be possible to have this in a single BTRFS, but… I give up the separation of operating system and home device thus making it more difficult to reinstall the operating system in case it would be needed – I don´t know how good BTRFS support is in the installer meanwhile – and probably increasing risk of data loss in case of filesystem troubles. Right now when /-device would break, it doesn´t affect /home. Having both as a subvolume if one breaks it is more likely that it affects the other one as well. Thanks, -- Martin
