Add new scripts

Signed-off-by: Florian Pritz <bluewind@xinu.at>

1 files changed, 31 insertions, 0 deletions

diff --git a/dd-parallel b/dd-parallel
new file mode 100755
index 0000000..0745225
--- /dev/null
+++ b/dd-parallel
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+# Run multiple dd processes in parallel to copy a single file/blockdevice. Each
+# dd process will operate on a dedicated part of the file at a time (1GB chunks
+# for big files).
+
+set -e
+
+# Source: https://stackoverflow.com/a/25268449
+min() {
+    printf "%s\n" "${@:2}" | sort "$1" | head -n1
+}
+max() {
+    # using sort's -r (reverse) option - using tail instead of head is also possible
+    min "${1}r" "${@:2}"
+}
+
+inputfile=$1
+if [[ -b "$inputfile" ]]; then
+	inputsize=$(blockdev --getsize64 "$inputfile")
+else
+	inputsize=$(stat --format %s "$inputfile")
+fi
+outputfile=$2
+
+stepsize=1000
+parallel=6
+# 1GB blocks or smaller blocks if we cannot achieve the required parallelization with 1GB
+blocksize=$(min -g 1000000 "$((inputsize / stepsize / parallel))" )
+
+seq 0 $stepsize $(($inputsize / $blocksize )) | xargs -P$parallel -I{} dd if="$inputfile" bs=$blocksize skip={} conv=sparse seek={} count=$stepsize status=none of="$outputfile"