From 0dbeebc37f9fd6b10742c669ff423da06fecf7c7 Mon Sep 17 00:00:00 2001
From: Lonnie Olson <lonnie.olson@elwoodstaffing.com>
Date: Tue, 29 Apr 2014 14:04:24 -0600
Subject: [PATCH 1/2] Add option --utc to use UTC dates in snapshot names
 instead of the local time zone.

---
 src/zfs-auto-snapshot.sh | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/zfs-auto-snapshot.sh b/src/zfs-auto-snapshot.sh
index e60a437..cff1116 100755
--- a/src/zfs-auto-snapshot.sh
+++ b/src/zfs-auto-snapshot.sh
@@ -38,6 +38,7 @@ opt_sep='_'
 opt_setauto=''
 opt_syslog=''
 opt_skip_scrub=''
+opt_utc=''
 opt_verbose=''
 
 # Global summary statistics.
@@ -62,6 +63,7 @@ print_usage ()
   -k, --keep=NUM     Keep NUM recent snapshots and destroy older snapshots.
   -l, --label=LAB    LAB is usually 'hourly', 'daily', or 'monthly'.
   -p, --prefix=PRE   PRE is 'zfs-auto-snap' by default.
+      --utc          Use UTC times in snapshot names.
   -q, --quiet        Suppress warnings and notices at the console.
       --send-full=F  Send zfs full backup. Unimplemented.
       --send-incr=F  Send zfs incremental backup. Unimplemented.
@@ -196,7 +198,7 @@ do_snapshots () # properties, flags, snapname, oldglob, [targets...]
 
 GETOPT=$(getopt \
   --longoptions=default-exclude,dry-run,fast,skip-scrub,recursive \
-  --longoptions=event:,keep:,label:,prefix:,sep: \
+  --longoptions=event:,keep:,label:,prefix:,sep:,utc \
   --longoptions=debug,help,quiet,syslog,verbose \
   --options=dnshe:l:k:p:rs:qgv \
   -- "$@" ) \
@@ -272,6 +274,10 @@ do
 			opt_prefix="$2"
 			shift 2
 			;;
+		(--utc)
+			opt_utc='--utc'
+			shift 1
+			;;
 		(-q|--quiet)
 			opt_debug=''
 			opt_quiet='1'
@@ -504,7 +510,7 @@ SNAPPROP="-o com.sun:auto-snapshot-desc='$opt_event'"
 
 # ISO style date; fifteen characters: YYYY-MM-DD-HHMM
 # On Solaris %H%M expands to 12h34.
-DATE=$(date --utc +%F-%H%M)
+DATE=$(date $opt_utc +%F-%H%M)
 
 # The snapshot name after the @ symbol.
 SNAPNAME="$opt_prefix${opt_label:+$opt_sep$opt_label}-$DATE"

From bd681482581c299a47682c6ea1f3ee9699c352a2 Mon Sep 17 00:00:00 2001
From: Lonnie Olson <lonnie.olson@elwoodstaffing.com>
Date: Wed, 30 Apr 2014 15:39:20 -0600
Subject: [PATCH 2/2] Snapshot name collision handling.

Handle snapshot name collisions by destroying the previous snapshot.
---
 src/zfs-auto-snapshot.sh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/zfs-auto-snapshot.sh b/src/zfs-auto-snapshot.sh
index cff1116..3252b81 100755
--- a/src/zfs-auto-snapshot.sh
+++ b/src/zfs-auto-snapshot.sh
@@ -158,6 +158,10 @@ do_snapshots () # properties, flags, snapname, oldglob, [targets...]
 
 	for ii in $TARGETS
 	do
+        if echo $SNAPSHOTS_OLD | grep -q "$ii@$NAME"
+        then
+            do_run "zfs destroy $FLAGS '$ii@$NAME'"
+        fi
 		if do_run "zfs snapshot $PROPS $FLAGS '$ii@$NAME'" 
 		then
 			SNAPSHOT_COUNT=$(( $SNAPSHOT_COUNT + 1 ))