The jukebox creates a dedicated target with one SBC device (removable media)
and one media changer with some storage element slots attached.
The jukebox script can be used to take "snapshots" of a different file (a production LUN
exported via a different target?) and expose these snapshots through the snapshot target.
This allows you to do things such as
* export a production LUN to an initiator
* from cron, take a snapshot of the production LUN every xyz
* export the snapshots via the snapshot target to a different host to do xyz
* the other host can then pick and chose which snapshot from the production LUN
it wants to access.
Signed-off-by: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
---
doc/README.sbcjukebox | 137 +++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 137 insertions(+), 0 deletions(-)
create mode 100755 doc/README.sbcjukebox
diff --git a/doc/README.sbcjukebox b/doc/README.sbcjukebox
new file mode 100755
index 0000000..87bf73c
--- /dev/null
+++ b/doc/README.sbcjukebox
@@ -0,0 +1,137 @@
+#!/bin/sh
+# EXAMPLE of sbc jukebox
+#
+# This is a simple script to create and drive a sbcjukebox that contains
+# the $NUMSLOT most recent snapshots of a production SBC LUN.
+# It requires that you store the LUN files on a filesystem that can create
+# file level cow snapshots using "cp --reflink".
+# On linux this is supported on BTRFS and possibly other filesystems too.
+#
+# It creates a new target with one SBC decice and a mediachanger.
+#
+#
+# TID is the target id to use
+# TNAME is the target iqn name to use
+# FILE is the backing store file for a production LUN. This file must reside on
+# a cow snapshot capable filesystem.
+# SNAPDIR is where we keep the SMC media file as well as where all snapshots are
+# kept. This must be the same filesystem as FILE
+# NUMSLOTS is how many old snapshots we want to keep.
+
+# sbcjukebox.sh start
+# to create the target and populate the storage elements.
+#
+# sbcjukebox.sh list
+# to show which snapshots are available
+#
+# sbcjukebox.sh snapshot
+# to take a new snapshot of the production LUN
+#
+
+
+
+TID=2
+TNAME="iqn.ronnie.test-snapshot"
+FILE="/data/RHEL6/RHEL6-1.img"
+SNAPDIR="${FILE}.snapshots"
+NUMSLOTS=8
+
+
+
+[ -d "$SNAPDIR" ] || mkdir "$SNAPDIR"
+
+usage() {
+ echo "sbcjukebox {start|list|snapshot|usage}"
+}
+
+prune_old_snapshots() {
+ ls $SNAPDIR | egrep -v "^smc$" | sort -n -r | tail -n +${NUMSLOTS} | while read OLD; do
+ echo "Deleting old snapshot $OLD"
+ rm -f ${SNAPDIR}/${OLD}
+ done
+}
+
+populate_elements() {
+ ELEMENT=1024
+ SNAPSHOTS=`ls $SNAPDIR | egrep -v "^smc$" | sort -n | head -n ${NUMSLOTS}`
+ for SNAP in $SNAPSHOTS; do
+ tgtadm --mode logicalunit --op update --tid $TID --lun 2 --params element_type=2,address=$ELEMENT,barcode=$SNAP,sides=1
+ ELEMENT=`expr "$ELEMENT" "+" "1"`
+ done
+
+ LAST=`expr "1024" "+" "$NUMSLOTS"`
+ while [ $ELEMENT -lt $LAST ]; do
+ tgtadm --mode logicalunit --op update --tid $TID --lun 2 --params element_type=2,address=$ELEMENT,clear_slot=1
+ ELEMENT=`expr "$ELEMENT" "+" "1"`
+ done
+
+ tgtadm --mode logicalunit --op update --tid $TID --lun 2 --params element_type=2,address=`expr "$LAST" "-" "1"`,clear_slot=1
+}
+
+snapshot() {
+ SNAP=`date +"%y%m%d%H%M"`
+
+ echo Create snapshot $SNAP
+ cp --reflink $FILE $SNAPDIR/$SNAP
+
+ prune_old_snapshots
+ populate_elements
+}
+
+list() {
+ echo Snapshots:
+ ls $SNAPDIR | egrep -v "^smc$"
+}
+
+start() {
+ #create a target
+ tgtadm --lld iscsi --op new --mode target --tid $TID -T $TNAME
+
+ # create the data transfer device
+ tgtadm --op new --mode logicalunit --tid $TID --lun 1 -Y disk
+ tgtadm --op update --mode logicalunit --tid $TID --lun 1 --params vendor_id=STGT,product_id=SNAPSHOT_SBC,product_rev=0010
+
+ # create backing store for SMC
+ [ -f "${SNAPDIR}/smc" ] || dd if=/dev/zero of="${SNAPDIR}/smc" bs=1k count=1
+
+ # create the media changer
+ tgtadm --op new --mode logicalunit --tid $TID --lun 2 -b "${SNAPDIR}/smc" --device-type=changer
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params vendor_id=STGT,product_id=SNAPSHOT_SMC,product_rev=0010,removable=1
+
+ # Add a Data Transfer devices (1 drive)
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params element_type=4,start_address=1,quantity=1
+
+ # Specify that the DISK above (LUN 1) is the data transfer device
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params element_type=4,address=1,tid=$TID,lun=1
+
+ # Medium Transport Elements (robot arm / picker)
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params element_type=1,start_address=16,quantity=1
+
+ # define path to virtual media
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params media_home=${SNAPDIR}
+
+ # create the storage elements
+ tgtadm --op update --mode logicalunit --tid $TID --lun 2 --params element_type=2,start_address=1024,quantity=$NUMSLOTS
+
+ prune_old_snapshots
+ populate_elements
+
+ tgtadm --lld iscsi --op bind --mode target --tid $TID -I ALL
+ tgtadm --lld iscsi --op show --mode target
+}
+
+case "$1" in
+start)
+ start
+ ;;
+snapshot)
+ snapshot
+ ;;
+list)
+ list
+ ;;
+*)
+ usage
+ ;;
+esac
+
--
1.7.3.1
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