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Re: Debian 8 and Debian 9 Dual Boot

On 29 November 2017 at 03:15, Dan Norton <dnorton@mindspring.com> wrote:

On 11/13/2017 01:55 PM, Joe wrote:
On Mon, 13 Nov 2017 11:01:27 -0500
Dan Norton <dnorton@mindspring.com> wrote:

Although I didn't say so, each install would have its own set of 
directories. Please say more about how to mount the other
installation and share data. How to mount things in another volume

Good advice so far, but to add a bit: all LVM groups will be seen at
boot, and /dev will know about them. See man lvm2 and also here:

https://wiki.debian.org/LVM  for complete information about the
commands you have available. There are also numerous tutorials on the
Net which show basic usage of the simpler commands. It's worth having a
look when you have some spare time, as one day you'll need to know some
of this and won't have any spare time.

Reading the wiki reveals "Grub and ?LiLo are not compatible with LVM, so /boot should be outside the storage disk managed by LVM." Here's what I have:

Attempts to boot normally do not work. But using Super Grub2 on a bootable cd and selecting "Boot manually" and picking the hd1 entry brings up the jessie system that the installer reports as successfully installed on sda3. Using fdisk to take a look:

dan@debian8:~$ sudo fdisk /dev/sda
Command (m for help): p
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: A615A904-0620-459F-BF44-5E53E54FDF24

Device         Start        End    Sectors   Size Type
/dev/sda1       2048     411647     409600   200M BIOS boot
/dev/sda2     411648   16783359   16371712   7.8G Linux swap
/dev/sda3   16783360  151001087  134217728    64G Linux LVM
/dev/sda4  151001088  285218815  134217728    64G Linux LVM
/dev/sda5  285218816  419436543  134217728    64G Linux LVM
/dev/sda6  419436544  553654271  134217728    64G Linux LVM
/dev/sda7  553654272 1953525134 1399870863 667.5G Linux filesystem

Is there a problem here?

​I have been using Supergrub for ages now.   If you use Gentoo as I do you appreciate the irritation of continuous babysitting of grub2 every time
you reconfigure the kernel (e.g. after setting up the long winded nonsense required to make a firewall work properly) then grub tends to go awol
and requires TLC, massage therapy and soft music to start working properly. 

Meanwhile you will feel so frustrated that you want to chew on barbed wire etc.

But supergrub is cool.  It is like a bloodhound.  You just can't fool it.  ​

The more you use it the dumber you feel using grub2 until you have finally sorted the gripes and things have calmed down and stabilised - usually a month later.

Remember the scene from 2001 space odyssey where the monkey throws the bones up in the air.....
​Do the same with grub2, then use supergrub until things work and then de-evolve again and vegetate in this area as I do.



dan@debian8:~$ df -h
Filesystem                    Size  Used Avail Use% Mounted on
/dev/dm-0                     9.1G  3.0G  5.7G  35% /
udev                           10M     0   10M   0% /dev
tmpfs                         775M  9.0M  766M   2% /run
tmpfs                         1.9G   68K  1.9G   1% /dev/shm
tmpfs                         5.0M  4.0K  5.0M   1% /run/lock
tmpfs                         1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda1                     992K  142K  851K  15% /boot/efi
/dev/mapper/debian8--vg-var   8.2G  1.3G  6.4G  17% /var
/dev/mapper/debian8--vg-home  9.1G  356M  8.3G   5% /home
/dev/mapper/debian8--vg-tmp   268M  2.1M  247M   1% /tmp
tmpfs                         388M  4.0K  388M   1% /run/user/115
tmpfs                         388M   12K  388M   1% /run/user/1000

Doesn't this satisfy the statement that "/boot should be outside the storage disk managed by LVM" since it is on sda1?

Look in /etc/fstab for lines beginning /dev/mapper/[volume] which will
be the volumes mounted in the running installation. The 'mapper' is
turning LVM volumes into things which look like partitions for many

Here is fstab:
# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/mapper/debian8--vg-root /              ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/sda1 during installation
UUID=B07E-1F0B  /boot/efi       vfat    umask=0077      0       1
/dev/mapper/debian8--vg-home /home          ext4    defaults        0       2
/dev/mapper/debian8--vg-tmp /tmp            ext4    defaults        0       2
/dev/mapper/debian8--vg-var /var            ext4    defaults        0       2
# swap was on /dev/sda2 during installation
UUID=6aa1846f-34dd-424d-b02c-dbd0af037a23 none            swap    sw              0       0
/dev/sr0        /media/cdrom0   udf,iso9660 user,noauto     0       0

Why won't it boot normally, that is without using the bootable Grub2 cd?

 - Dan

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