Add media backup script

README.MD

@@ -0,0 +1,80 @@
+# LTO Backup Scripts
+
+Scripts to help me perform my backups to Ultrium LTO tapes.
+
+## Movies Library
+
+* `mkbak_media.sh`: Incremental subdirectory backup. Take each directory in my cwd, tar it, and append it to tape, one tape entry per directory. Create / extend a CSV index denoting when and to what tape ID the backup was made. Do not backup directories that were already backed up to other media (using the index). Note: Changes in directories will not be detected. The directory name is the only clue.
+
+# LTO Notes
+## General stuff
+* dev/nst does not auto-rewind, dev/st does
+* use mt-st seek / tell to position the tape at block indexes
+* Remaining capacity: https://serverfault.com/questions/853302/determine-remaining-capacity-of-lto-tape
+	* `sg_logs -a $DEV | sed -n 's/\s*Main partition remaining capacity (in MiB):\s*\(.*\)/\1/p'`
+* Disable compression: `mt-st -f /dev/nst0 compression 0`
+* Make seek/tell work: `mt-st -f /dev/nst0 stsetoptions scsi2logical`
+
+## Improve start/stop
+
+If you have a slow source / destination, consider using mbuffer with a size of a couple of Gigs. But that might also break speed matching, causing start / stop rather than going slower... idk.
+
+
+## Backups
+
+### Encrypted tar using GPG
+
+`tar cvO --exclude dir/excludeme dir/ | gpg --encrypt --sign --default-key KEY-ID -r KEY-ID -z 0 dd of=/dev/nst0 bs=512k`
+
+To decrypt, simply use `gpg --decrypt /dev/nst0`
+
+
+
+# LTFS on LTO-6
+My drives are a little weird, to get it to work I need to edit LTFS sources.
+
+`ltfs-2.4.3.1-10461/src/tape_drivers/linux/sg/sg_tape.c`: Type is incorrectly auto detected, we need to always `/* Use LogPage 0x31 */`
+
+See this patch for inspiration
+
+```
+diff --git a/src/tape_drivers/linux/sg/sg_tape.c b/src/tape_drivers/linux/sg/sg_tape.c
+index f583079..1169e44 100644
+--- a/src/tape_drivers/linux/sg/sg_tape.c
++++ b/src/tape_drivers/linux/sg/sg_tape.c
+@@ -513,6 +513,12 @@ static int _raw_open(struct sg_data *priv)
+ 		return -EDEV_DEVICE_UNSUPPORTABLE; /* Unsupported device */
+ 	}
+ 
++	/* Special care about Quantum model B */
++	if (priv->vendor == VENDOR_QUANTUM) {
++		if (id_data.product_id[7] == ' ')
++			priv->vendor = VENDOR_QUANTUM_B;
++	}
++
+ 	if (priv->drive_serial[0]) {
+ 		/* if serial number is already set, compare it */
+ 		if (strcmp(priv->drive_serial, id_data.unit_serial)) {
+@@ -2969,7 +2975,8 @@ int sg_remaining_capacity(void *device, struct tc_remaining_cap *cap)
+ 	memset(buffer, 0, LOGSENSEPAGE);
+ 
+ 	if ((IS_LTO(priv->drive_type) && (DRIVE_GEN(priv->drive_type) == 0x05)) ||
+-		(priv->vendor == VENDOR_HP && IS_LTO(priv->drive_type) && (DRIVE_GEN(priv->drive_type) == 0x06))) {
++		(priv->vendor == VENDOR_HP && IS_LTO(priv->drive_type) && (DRIVE_GEN(priv->drive_type) == 0x06)) ||
++		(priv->vendor == VENDOR_QUANTUM_B && IS_LTO(priv->drive_type))) {
+ 
+ 		/* Use LogPage 0x31 */
+ 		ret = sg_logsense(device, (uint8_t)LOG_TAPECAPACITY, (uint8_t)0, (void *)buffer, LOGSENSEPAGE);
+diff --git a/src/tape_drivers/tape_drivers.h b/src/tape_drivers/tape_drivers.h
+index a9d7bf5..6e11771 100644
+--- a/src/tape_drivers/tape_drivers.h
++++ b/src/tape_drivers/tape_drivers.h
+@@ -178,6 +178,7 @@ enum {
+ 	VENDOR_IBM,
+ 	VENDOR_HP,
+ 	VENDOR_QUANTUM,
++	VENDOR_QUANTUM_B,
+ };
+ 
+ enum {
+```

mkbak_media.sh

@@ -0,0 +1,95 @@
+#!/bin/bash
+
+MEDIA_ID="$1"
+MODE="append"
+DEV="/dev/nst0"
+LIB="./lib.csv"
+
+if [ "$2" != "" ]; then
+	MODE="$2"
+fi
+
+function info()
+{
+	echo -e "\e[34m[I] $1\e[0m"
+}
+
+function warn()
+{
+	echo -e "\e[33m[W] $1\e[0m"
+}
+
+function err()
+{
+	echo -e "\e[31m[E] $1\e[0m"
+}
+
+function succ()
+{
+	echo -e "\e[32m[ ] $1\e[0m"
+}
+
+if [ "$MEDIA_ID" == "" ]; then
+	echo "usage: $0 <media ID> [rewind]"
+	exit
+fi
+
+info "Backing up new directories to $MEDIA_ID in $DEV."
+
+if [ ! -f "$LIB" ]; then
+	echo "Directory;Media ID;Date" > $LIB
+fi
+
+info "Configuring tape drive"
+# mt-st -f $DEV stsetoptions scsi2logical
+mt-st -f $DEV compression 0
+
+if [ "$MODE" == "append" ]; then
+	info "Moving tape to end..."
+	mt-st -f $DEV eod
+else
+	warn "Rewinding tape. This will delete all existing data on tape. Are you sure? [ctrl+c to cancel]"
+	read a
+	mt-st -f $DEV rewind
+fi
+
+skipped=0
+for dir in *; do
+	if [ ! -d "$dir" ]; then
+		continue
+	fi
+	exist=`cat "$LIB" | grep "^$dir;"`
+	if [ "$exist" != "" ]; then
+		info "Skipping $dir. Already backed up: $exist"
+		continue
+	fi
+	echo ""
+	info "Attempting to backup $dir"
+	lsize=`du -s "$dir" | sed "s/\s.*//"`
+	lsize=$(($lsize / 1024))
+	rsize=`sg_logs -a $DEV | sed -n 's/\s*Main partition remaining capacity (in MiB):\s*\(.*\)/\1/p'`
+	if [ $lsize -gt $rsize ]; then
+		skipped=$((skipped+1))
+		warn "Not enough space left on device (${rsize} MB remaining, ${lsize} MB required). Trying next directory."
+		continue;
+	fi
+	info "Appending $dir to tape ($lsize MB, $rsize MB available)"
+	tar cvO "$dir" | dd of=$DEV bs=512k
+	if [ $? -ne 0 ]; then
+		err "An error occured writing the backup to tape. Aborting."
+		exit
+	fi
+	date=`date`
+	echo "$dir;$MEDIA_ID;$date" >> $LIB
+done
+
+info "Rewinding and ejecting tape"
+mt-st -f $DEV rewoff
+
+echo ""
+if [ $skipped -eq 0 ]; then
+	succ "Backup complete. All directories are on tape."
+else
+	succ "Tape complete, but there is more data to be backed up."
+	warn "Insert a new tape and rerun the script to complete the backup."
+fi