Fedora & RHEL: fix slow loading mpt3sas.

Credit: @mdiepart from #282

Closes #282 #262

Fix variable export before chroot

Credit: @mdiepart from #282

remind user to enable multi-disk support

NixOS: handle installation failure wrt encrypted boot pool

Closes #279
Signed-off-by: Maurice Zhou <jasper@apvc.uk>

docs/Getting Started/Fedora/Root on ZFS/3-system-configuration.rst

@@ -31,6 +31,12 @@ System Configuration
 
     echo 'add_dracutmodules+=" zfs "' > /mnt/etc/dracut.conf.d/zfs.conf
 
+#. Force load mpt3sas module if used::
+
+     if grep -q mpt3sas /proc/modules; then
+       echo 'forced_drivers+=" mpt3sas "'  > /mnt/etc/dracut.conf.d/zfs.conf
+     fi
+
 #. Enable timezone sync::
 
     hwclock --systohc
@@ -84,7 +90,7 @@ System Configuration
     INST_ID=$INST_ID
     unalias -a
     INST_VDEV=$INST_VDEV
-    DISK=$DISK" > /mnt/root/chroot
+    DISK=\"$DISK\"" > /mnt/root/chroot
     arch-chroot /mnt bash --login
 
 #. Source variables::