safer implementation
This commit is contained in:
@@ -1,62 +1,28 @@
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#!/bin/sh
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opt_prefix='zfs-auto-snap'
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opt_keep=10
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opt_label="defaultLabel"
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opt_threshold=0
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# ==============================================================================
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# Phase 1: Default Configuration
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# ==============================================================================
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# Default fallback settings if not provided via command-line flags.
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opt_prefix='zfs-auto-snap' # Prefix prepended to all snapshot names
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opt_keep=10 # Number of snapshots to retain
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opt_label='defaultLabel' # Snapshot label tag (e.g. quarterhour, hourly, daily)
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opt_threshold=0 # Written bytes required to trigger snapshot (0 = disabled)
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do_snapshots ()
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{
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local KEEP=''
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for ii in $TARGETS
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do
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KEEP="$opt_keep"
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if [ "$opt_threshold" -eq 0 ]
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then
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zfs snapshot "$ii@$SNAPNAME"
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else
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bytes_written=`zfs get -Hp -o value written $ii`
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if [ "$bytes_written" -ge "$opt_threshold" ]
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then
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zfs snapshot "$ii@$SNAPNAME"
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else
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KEEP=$(( $KEEP + 1 ))
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fi
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fi
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# ASSERT: The old snapshot list is sorted by increasing age.
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for jj in $SNAPSHOTS_OLD
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do
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# Check whether this is an old snapshot of the filesystem.
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if [ -z "${jj#$ii@$SNAPGLOB}" ]
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then
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KEEP=$(( $KEEP - 1 ))
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if [ "$KEEP" -le '0' ]
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then
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zfs destroy -d "$jj"
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fi
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fi
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done
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done
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}
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# main ()
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# {
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while [ "$#" -gt '0' ]
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do
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case "$1" in
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# ==============================================================================
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# Phase 2: Command-Line Argument Parsing
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# ==============================================================================
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# Parse options passed to the script (--label, --keep, --threshold, --prefix).
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while [ "$#" -gt 0 ]; do
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case "$1" in
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--keep)
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if [ ! "$2" -gt '0' ];
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then
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echo "keep parameters need to be greater than 0"
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exit 1
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fi
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# Ensure keep count is a valid positive integer
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case "$2" in
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''|*[!0-9]*|0)
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echo "Error: --keep requires a number greater than 0" >&2
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exit 1
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;;
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esac
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opt_keep="$2"
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shift 2
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;;
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@@ -65,67 +31,132 @@ do
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shift 2
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;;
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--threshold)
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if [ ! "$2" -ge '0' ];
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then
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echo "threshold parameters need to be equal or greater than 0"
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exit 1
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fi
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# Ensure threshold is a valid non-negative integer (in bytes)
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case "$2" in
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''|*[!0-9]*)
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echo "Error: --threshold requires a number equal or greater than 0" >&2
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exit 1
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;;
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esac
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opt_threshold="$2"
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shift 2
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;;
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--prefix)
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opt_prefix="$2"
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shift 2
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;;
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*)
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# Display usage and exit if an unknown option is encountered
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echo "Usage: $0 [--label LABEL] [--keep NUM] [--threshold BYTES] [--prefix PREFIX]" >&2
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exit 1
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;;
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esac
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done
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ZPOOL_STATUS=$(env LC_ALL=C zpool status 2>&1 )
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ZFS_LIST=$(env LC_ALL=C zfs list -t volume,filesystem -H)
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CANDIDATES=$(echo "$ZFS_LIST" | awk -F '\t' '{print $1}')
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SNAPSHOTS_OLD=$(env LC_ALL=C zfs list -H -t snapshot -S creation -o name)
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# ==============================================================================
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# Phase 3: Inspect ZFS Pools and Datasets
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# ==============================================================================
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# Query zpool status once to check pool states and active operations.
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ZPOOL_STATUS=$(env LC_ALL=C zpool status 2>&1)
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# Get a list of pools that are being scrubbed.
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ZPOOLS_SCRUBBING=$(echo "$ZPOOL_STATUS" | awk -F ': ' \
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'$1 ~ /^ *pool$/ { pool = $2 } ; \
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$1 ~ /^ *scan$/ && $2 ~ /scrub in progress/ { print pool }' \
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| sort )
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# Identify pools that should NOT receive snapshots:
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# - Pools currently running a scrub (to avoid additional I/O load).
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# - Pools in unhealthy states (anything other than ONLINE or DEGRADED).
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ZPOOLS_EXCLUDED=$(echo "$ZPOOL_STATUS" | awk -F ': ' '
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$1 ~ /^ *pool$/ { pool = $2 }
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$1 ~ /^ *scan$/ && $2 ~ /scrub in progress/ { print pool }
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$1 ~ /^ *state$/ && $2 !~ /ONLINE|DEGRADED/ { print pool }
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' | sort -u)
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# Get a list of pools that cannot do a snapshot.
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ZPOOLS_NOTREADY=$(echo "$ZPOOL_STATUS" | awk -F ': ' \
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'$1 ~ /^ *pool$/ { pool = $2 } ; \
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$1 ~ /^ *state$/ && $2 !~ /ONLINE|DEGRADED/ { print pool } ' \
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| sort)
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# Retrieve list of all candidate ZFS filesystems and volumes.
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CANDIDATES=$(env LC_ALL=C zfs list -H -o name -t filesystem,volume)
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# Initialize the list of datasets that will get snapshots.
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# Retrieve all existing snapshots, sorted newest first (-S creation).
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SNAPSHOTS_OLD=$(env LC_ALL=C zfs list -H -o name -t snapshot -S creation)
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# ==============================================================================
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# Phase 4: Filter Target Datasets
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# ==============================================================================
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# Filter candidate datasets, skipping any that belong to an excluded pool.
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TARGETS=''
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for ii in $CANDIDATES; do
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# Extract root pool name from the dataset path (e.g. 'tank' from 'tank/data')
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pool="${ii%%/*}"
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skip=0
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for ii in $CANDIDATES
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do
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# Exclude datasets in pools that cannot do a snapshot.
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for jj in $ZPOOLS_NOTREADY
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do
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if [ "$(echo "$ii" | awk -F/ '{print $1}')" = "$jj" ]
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then
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continue 2
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fi
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done
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for jj in $ZPOOLS_SCRUBBING
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do
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if [ "$(echo "$ii" | awk -F/ '{print $1}')" = "$jj" ]
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then
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continue 2
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for jj in $ZPOOLS_EXCLUDED; do
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if [ "$pool" = "$jj" ]; then
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skip=1
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break
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fi
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done
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TARGETS="$TARGETS $ii"
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if [ "$skip" -eq 0 ]; then
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TARGETS="$TARGETS $ii"
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fi
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done
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# ==============================================================================
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# Phase 5: Generate Snapshot Names and Patterns
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# ==============================================================================
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# UTC timestamp formatted as YYYY-MM-DD-HH-MM (16 characters)
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DATE=$(date -u +%F-%H-%M)
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DATE=$(date --utc +%F-%H-%M)
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# Name for the new snapshot: <prefix>_<label>_<timestamp>
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SNAPNAME="${opt_prefix}_${opt_label}_$DATE"
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# The expression for matching old snapshots.
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# Pattern matching old snapshots with this prefix and label
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SNAPGLOB="${opt_prefix}_${opt_label}_????-??-??-??-??"
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do_snapshots "$SNAPNAME" "$SNAPGLOB" "$TARGETS"
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# ==============================================================================
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# Phase 6: Snapshot Creation and Pruning Function
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# ==============================================================================
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# For each target dataset: create new snapshot and prune old snapshots.
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do_snapshots ()
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{
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for ii in $TARGETS; do
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KEEP="$opt_keep"
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# Check write threshold if specified, or snapshot directly
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if [ "$opt_threshold" -eq 0 ]; then
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if ! zfs snapshot "$ii@$SNAPNAME"; then
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# If snapshot creation fails, skip pruning this dataset to prevent data loss
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continue
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fi
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else
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# Conditional snapshot: check bytes written since the last snapshot
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bytes_written=$(zfs get -Hp -o value written "$ii" 2>/dev/null)
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if [ -n "$bytes_written" ] && [ "$bytes_written" -ge "$opt_threshold" ] 2>/dev/null; then
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# Threshold reached: create new snapshot
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if ! zfs snapshot "$ii@$SNAPNAME"; then
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# If snapshot creation fails, skip pruning
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continue
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fi
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else
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# Threshold not met: no new snapshot taken, so increment KEEP
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# to preserve existing retained snapshots without deleting one
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KEEP=$(( KEEP + 1 ))
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fi
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fi
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# Prune older snapshots matching the current label and prefix.
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# Note: SNAPSHOTS_OLD is sorted newest to oldest.
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for jj in $SNAPSHOTS_OLD; do
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# Match snapshots belonging to dataset $ii with matching prefix and label
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if [ -z "${jj#$ii@$SNAPGLOB}" ]; then
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KEEP=$(( KEEP - 1 ))
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# Once the retention quota is exhausted, destroy excess older snapshots
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if [ "$KEEP" -le 0 ]; then
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zfs destroy -d "$jj"
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fi
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fi
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done
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done
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}
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# ==============================================================================
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# Phase 7: Execution
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# ==============================================================================
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do_snapshots
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exit 0
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# }
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