Enhancement to delete_snapshots

[sigxcpu76]

This will not work on SunOS platforms, so I've changed some bits:

• the timestamps used in snapshots list are UNIX timestamps now (-p parameter) for easy comparison
• the absolute oldest date computation is added for SunOS platform
• the "from " is not outputted anymore, because it is not in the snapshots list

--- delete_snapshots.sh Sat Dec  5 10:03:02 2015
+++ /opt/custom/sbin/delete_snapshots   Sat Dec  5 10:02:00 2015
@@ -79,6 +79,8 @@
   platform='bsd'
 elif [[ "$unamestr" == 'Darwin' ]]; then
   platform='bsd'
+elif [[ "$unamestr" == 'SunOS' ]]; then
+  platform='sunos'
 else
   echo -e "unknown platform $unamestr 1>&2"
   exit 1
@@ -93,6 +95,8 @@

 if [[ "$platform" == 'linux' ]]; then
 compare_timestamp=`date --date="-$(echo $compare_seconds) seconds" +"%s"`
+elif [[ "$platform" == 'sunos' ]]; then
+compare_timestamp=$((`date +"%s"` - $compare_seconds))
 else
 compare_timestamp=`date -j -v-$(echo $compare_seconds)S +"%s"`
 fi
@@ -99,7 +103,7 @@

 # get a list of snapshots sorted by creation date, so that we get the oldest first
 # This will allow us to skip the loop early
-snapshots=`zfs list -H -t snapshot -o name,creation -s creation | grep $pattern`
+snapshots=`zfs list -H -t snapshot -o name,creation -s creation -p | grep $pattern`

 if [[ -z $snapshots ]]; then
   echo "no snapshots found for pattern $pattern"
@@ -112,14 +116,8 @@
 IFS=$'\n'
 for line in $snapshots; do
   snapshot=`echo $line | cut -f 1`
-  creation_date=`echo $line | cut -f 2`
+  creation_date_timestamp=`echo $line | cut -f 2`

-  if [[ "$platform" == 'linux' ]]; then
-    creation_date_timestamp=`date --date="$creation_date" "+%s"`
-  else
-    creation_date_timestamp=`date -j -f "%a %b %d %H:%M %Y" "$creation_date" "+%s"`
-  fi
-
   # Check if the creation date of a snapshot is less than our compare date
   # Meaning if it is older than our compare date
   # It is younger, we can stop processing since we the list is sorted by
@@ -130,10 +128,10 @@
       echo "DELETE: $snapshot from $creation_date"
       zfs destroy $snapshot
     else
-      echo "WOULD DELETE: $snapshot from $creation_date"
+      echo "WOULD DELETE: $snapshot"
     fi
   else
-    echo "KEEP: $snapshot from $creation_date"
+    echo "KEEP: $snapshot"
     echo "No more snapshots to be processed for $pattern. Skipping.."
     break
   fi

[dtomilso]

Would you mind pasting a copy of the script with the changes?
This is breaking for me when trying to run on Solaris 11.4 December 2020 SRU.

[sigxcpu76]

I've moved away from Illumos for 5 years now :)
I highly recommend a "keep the last N snaphots" pattern instead of deleting by date.

Nowadays I use the following script to cleanup by the above mentioned pattern.

#!/bin/bash

ROOT_DS=slow
KEEP=3

for i in $(zfs list -H -r $ROOT_DS -o name); do
	for s in $(zfs list -S creation -H -t snapshot -o name $i | tail -n +${KEEP}); do
		echo "Deleting $s"
		zfs destroy $s
	done
done

tail in SunOS may be different, so you need to test. That syntax is used to display the last lines except .
few($KEEP)