From: Andre Noll <maan@tuebingen.mpg.de>
Date: Sun, 24 Aug 2025 11:25:16 +0000 (+0200)
Subject: Add an example to generate a random XFS UUID to man page.
X-Git-Tag: v1.0.1^0
X-Git-Url: https://git.tuebingen.mpg.de/?a=commitdiff_plain;h=refs%2Fheads%2Fmaster;p=misma.git

Add an example to generate a random XFS UUID to man page.

This alternative to the "mount -o nouuid" approach is useful for long-lived
snapshots.
---

diff --git a/misma.suite.m4 b/misma.suite.m4
index 46493fd..41893f9 100644
--- a/misma.suite.m4
+++ b/misma.suite.m4
@@ -449,15 +449,12 @@
 	.I activate
 	the snapshot logical volume to create the corresponding device node.
 
-	Moreover, the XFS filesystem driver refuses to mount a block device
-	which contains a UUID that is identical to the UUID of an already
-	mounted filesystem. To mount a snapshot of an XFS filesystem, one
-	must therefore tell XFS to skip the UUID check.
+	Moreover, the XFS filesystem driver refuses to mount a filesystem whose
+	UUID is identical to the UUID of an already mounted filesystem. To mount a
+	snapshot of a mounted XFS filesystem, one must therefore either change the
+	UUID of the snapshot, or ask XFS to skip the UUID check.
 
-	See the examples below for suitable command line options for
-	.BR lvchange (8)
-	and
-	. BR mount (8).
+	See the examples below for suitable commands to work around these issues.
 
 	Since logical volumes which contain a mounted filesystem cannot be
 	removed, a thin pool which is not overbooked may still run out of
@@ -541,7 +538,16 @@
 	.EE
 	.RE
 	.IP \(bu 2
-	Mount an active snapshot which contains an XFS filesystem:
+	Replace the UUID of the XFS filesystem stored on a snapshot with a random UUID:
+
+	.RS 6
+	.EX
+		.B xfs_admin \-U generate /dev/vg/misma-tlv.42
+	.EE
+	.RE
+	.IP \(bu 2
+	Mount an active snapshot which contains an XFS filesystem, ignoring duplicate
+	UUIDs:
 
 	.RS 6
 	.EX