adding partoff

shell/partoff.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+#
+# Calculate the optimal starting partition offset for a block device
+#
+# SPDX-License-Identifier: MIT
+
+if [[ $# -ne 1 ]] || [[ ! -d /sys/block/${1} ]]; then
+  _BLKDEVS="["
+  for ii in /sys/block/*; do
+    _BLKDEVS+=" ${ii##*/}"
+  done
+  _BLKDEVS+=" ]"
+  echo "Block devices detected: ${_BLKDEVS}"
+  echo " Usage: $0 <block device>"
+  echo " Example: $0 sda"
+  exit 1
+fi
+
+OPT=$(cat "/sys/block/${1}/queue/optimal_io_size")
+OFF=$(cat "/sys/block/${1}/alignment_offset")
+BLK=$(cat "/sys/block/${1}/queue/physical_block_size")
+
+# shellcheck disable=SC2004
+if [[ ${OPT} -eq 0 ]]; then
+  echo "Optimal I/O is zero, use 2048s (sectors)"
+else
+  _RES=$(( ($OPT+$OFF)/$BLK ))
+  # ensure minimum 2048s offset
+  while [[ ${_RES} -lt 2048 ]]; do
+    _RES=$(( ${_RES}+${_RES} ))
+  done
+  echo "Optimal I/O is set, use ${_RES}s (sectors)"
+fi
+
+exit 0