Author: David Teigland <teigland(a)redhat.com>
AuthorDate: Thu Mar 5 12:12:42 2015 -0600
Committer: David Teigland <teigland(a)redhat.com>
CommitterDate: Thu Mar 5 12:12:42 2015 -0600
man: add info to lvmsystemid
about losing access to a VG if lvm is downgraded
to an earlier version.
man/lvmsystemid.7.in | 21 ++++++++++++++-------
1 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/man/lvmsystemid.7.in b/man/lvmsystemid.7.in
index 0881b1e..76b0e83 100644
@@ -42,13 +42,7 @@ maximum length of a system_id is 128 characters.
To benefit fully from system_id, all hosts must have system_id set, and
VGs must have system_id set. A VG on shared storage can be damaged or
-destroyed in the following cases which the user must be careful to avoid:
-.IP \[bu] 2
-A host using an old version of lvm without the system_id feature will not
-recognize the system_id of other hosts' VGs. VGs with a new system_id
-are nominally protected from old versions of lvm by appearing to be
-read-only to the old versions.
+destroyed in some cases which the user must be careful to avoid.
.IP \[bu] 2
A VG without a system_id can be used without restriction from any host,
@@ -73,6 +67,19 @@ operations and corrupting the PVs. See the
section for more information.
+.IP \[bu] 2
+A host using an old version of lvm without the system_id feature will not
+recognize a new system_id in VGs from other hosts. Even though the old
+version of lvm is not blocked from reading a VG with a system_id, it is
+blocked from writing to the VG (or its LVs). The new system_id changes
+the write mode of a VG, making it appear read-only to previous lvm
+This also means that if a host downgrades its version of lvm, it would
+lose access to any VGs it had created with a system_id. To avoid this,
+the system_id should be removed from VGs before downgrading to an lvm
+version without the system_id feature.
.SS Types of VG access