Debian: Use pinning for stretch-backports

This ensures that updates in stretch-backports will be installed.

I also made Debian.md and Debian-Stretch-Root-on-ZFS.md consistent with
their setup of sources.

I'm keeping the simpler setup in the Live CD environment, as that is
only temporary.

Debian-Stretch-Root-on-ZFS.md

@@ -41,7 +41,7 @@ If you have a second system, using SSH to access the target system can be conven
 
     $ sudo -i
 
-1.4  Add `contrib` archive area:
+1.4  Setup and update the repositories:
 
     # echo deb http://deb.debian.org/debian stretch contrib >> /etc/apt/sources.list
     # echo deb http://deb.debian.org/debian stretch-backports main contrib >> /etc/apt/sources.list
@@ -53,6 +53,8 @@ If you have a second system, using SSH to access the target system can be conven
     # apt install --yes -t stretch-backports zfs-dkms
     # modprobe zfs
 
+* The dkms dependency is installed manually just so it comes from stretch and not stretch-backports. This is not critical.
+
 ## Step 2: Disk Formatting
 
 2.1  If you are re-using a disk, clear it as necessary:
@@ -270,9 +272,15 @@ Customize this file if the system is not a DHCP client.
     deb http://deb.debian.org/debian stretch main contrib
     deb-src http://deb.debian.org/debian stretch main contrib
 
+    # vi /etc/apt/sources.list.d/stretch-backports.list
     deb http://deb.debian.org/debian stretch-backports main contrib
     deb-src http://deb.debian.org/debian stretch-backports main contrib
 
+    # vi /etc/apt/preferences.d/90_zfs
+    Package: libnvpair1linux libuutil1linux libzfs2linux libzpool2linux spl-dkms zfs-dkms zfs-test zfsutils-linux zfsutils-linux-dev zfs-zed
+    Pin: release n=stretch-backports
+    Pin-Priority: 990
+
 4.4  Bind the virtual filesystems from the LiveCD environment to the new system and `chroot` into it:
 
     # mount --rbind /dev  /mnt/dev
@@ -296,8 +304,8 @@ Even if you prefer a non-English system language, always ensure that `en_US.UTF-
 
 4.6  Install ZFS in the chroot environment for the new system:
 
-    # apt install --yes dkms dpkg-dev linux-headers-$(uname -r) linux-image-amd64
-    # apt install --yes -t stretch-backports zfs-initramfs
+    # apt install --yes dpkg-dev linux-headers-$(uname -r) linux-image-amd64
+    # apt install --yes zfs-initramfs
 
 4.7  For LUKS installs only:
 

Debian.md

@@ -11,25 +11,30 @@ Offical ZFS on Linux [DKMS](https://en.wikipedia.org/wiki/Dynamic_Kernel_Module_
 ## Installation
 For Debian Stretch, ZFS packages are included in the [contrib repository](https://packages.debian.org/source/stretch/zfs-linux). Newer ZFS packages are provided by the [backports repository](https://backports.debian.org/Instructions/).
 
+If you want to boot from ZFS, see [[Debian Stretch Root on ZFS]] instead.
+
 Add the backports repository:
 
-        # echo "deb http://deb.debian.org/debian stretch-backports main contrib" > /etc/apt/sources.list.d/stretch-backports.list
+    # vi /etc/apt/sources.list.d/stretch-backports.list
+    deb http://deb.debian.org/debian stretch-backports main contrib
+    deb-src http://deb.debian.org/debian stretch-backports main contrib
+
+    # vi /etc/apt/preferences.d/90_zfs
+    Package: libnvpair1linux libuutil1linux libzfs2linux libzpool2linux spl-dkms zfs-dkms zfs-test zfsutils-linux zfsutils-linux-dev zfs-zed
+    Pin: release n=stretch-backports
+    Pin-Priority: 990
 
 Update the list of packages:
 
-        # apt update
+    # apt update
 
 Install the kernel headers and other dependencies:
 
-        # apt install linux-headers-$(uname -r) linux-headers-amd64 dkms build-essential libelf-dev
+    # apt install --yes dpkg-dev linux-headers-$(uname -r) linux-image-amd64
 
 Install the zfs packages:
 
-        # apt-get install -t stretch-backports zfs-dkms zfsutils-linux
-
-If you want to boot from ZFS (for more information, see [[Debian Stretch Root on ZFS]]), you'll need the `zfs-initramfs` package too:
-
-        # apt-get install -t stretch-backports zfs-initramfs
+    # apt-get install zfs-dkms zfsutils-linux
 
 ## Jessie to Stretch update
 From Debian Stretch packages are included in Debian official `contrib` repository. Steps to reinstall packages: