[Xen-devel] [PATCH OSSTEST 2/3] Debian: erase-other-disks: erase partitions first

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

It seems that when sdX is zeroed there is some chance that sdX[0-9]
will disappear before we get to them.

When partman comes along and recreates the partitions it is likely
that they will occupy the same disk space as before (since d-i's
autopartition is deterministic), meaning that LVM will find the old
PV headers again.

This is in particular problematic on multi disk systems where we end
up with an LV spanning sda5 and sdb. sdb is successfully erased here
but sda5 is not, however LVM will still find the LV with missing PV,
which is sufficient to trigger partman-lvm's checks for erasing
devices which weren't explicitly listed, resulting in:

    !! ERROR: Unable to automatically remove LVM data

    Because the volume group(s) on the selected device also consist of physical
    volumes on other devices, it is not considered safe to remove its LVM data
    automatically. If you wish to use this device for partitioning, please 
remove
    its LVM data first.

which cannot be preseeded around.

If the autopartitioning is not deterministic (as might be the case
when installing a different version of Debian to last time) then
going from layout A -> B -> A' risks B (by chance) not destroying the
headers created by A, meaning that A' will find them and suffer again
from the problem above. This is handled via the use of
ts-host-install-twice which will cause A' to run twice, i.e. A -> B
-> (A' -> A''). In this case A' will fail as above, but A'' will
startup seeing the partition layout put in place by A' (which matches
A) and erase those partitions, leading to success later on.

Also erase partitions for all sd/hd? not just sda+hda.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 Osstest/Debian.pm | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Osstest/Debian.pm b/Osstest/Debian.pm
index cf3486b..20f3de7 100644
--- a/Osstest/Debian.pm
+++ b/Osstest/Debian.pm
@@ -1057,12 +1057,13 @@ udevadm settle
 for sd in sd hd; do
     log "\${sd} devices present before: `echo /dev/\${sd}*`"
     for b in a b c d e f; do
+        for dev in /dev/\${sd}\${b}[0-9]; do
+            zero
+        done
+
         dev=/dev/\${sd}\${b}
         zero
     done
-    for dev in /dev/\${sd}a[0-9]; do
-        zero
-    done
     udevadm settle
     log "\${sd} devices present after: `echo /dev/\${sd}*`"
 done
-- 
2.6.1


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