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+---
+date: 2012-03-20
+title: Add SAN functions to Highly Available NFS/NAS
+category: linux
+---
+
+This based on my last post where I documented building a Highly
+Available NFS/NAS server.
+
+There is not a huge amount that needs to be done in order to add iSCSI
+functionality as well.
+
+Add a file called */etc/drbd/iscsi.res* containing:
+
+    resource iscsi {
+        on nfs1 {
+            device /dev/drbd1;
+            disk   /dev/vdc;
+            meta-disk internal;
+            address   10.0.0.1:7789;
+        }
+        on nfs2 {
+            device /dev/drbd1;
+            disk   /dev/vdc;
+            meta-disk internal;
+            address   10.0.0.2:7789;
+        }
+    }
+
+This differs from the previous resource in 2 ways. Obviously it using a
+different physical disk. Also the port number of the address is
+incremented; each resource has to have its own port to communicate on.
+
+# Configure Heartbeat
+
+Add a new resource to */etc/ha.d/haresources*:
+
+    iscsi1.snellwilcox.local IPaddr::10.0.0.101/24/eth0 drbddisk::iscsi tgtd
+
+Same primary host, new IP address, new drbd resource and of course the
+service to be controlled (tgtd in this case).
+
+I also made a couple of changes to */etc/ha.d/ha.cf*:
+
+    keepalive 500ms
+    deadtime 5
+    warntime 10
+    initdead 120
+
+This changes the regularity of the heartbeat packets from every 2
+seconds to 2 every second. We also say that a node is dead after only 5
+seconds rather than after 30.
+
+# Configure an iSCSI Target
+
+Tgtd has a config file that you can use in */etc/tgt/targets.conf*. It
+is an XML file, so add entry like:
+
+    <target iqn.2011-07.world.server:target0>
+            # provided devicce as a iSCSI target
+            backing-store /dev/vg_matthew/lv_iscsi1
+            # iSCSI Initiator's IP address you allow to connect
+            initiator-address 192.168.1.20
+            # authentication info ( set anyone you like for "username", "password" )
+    </target>
+
+The target name is by convention
+*iqn.year-month.reverse-domainname:hostname.targetname*. Each backing
+store will be a seperate LUN. A discussion of this is out of the scope
+of this article.
+
+By default, this config file is disabled. Enable it by un-commenting the
+line `#TGTD_CONFIG=/etc/tgt/targets.conf` in */etc/sysconfig/tgtd*. You
+can now enable the target with service tgtd reload.
+
+Now when you run `tgtadm –mode target –op show` you should get something
+like:
+
+    Target 1: iqn.2012-03.com.example:iscsi.target1
+        System information:
+            Driver: iscsi
+            State: ready
+        I_T nexus information:
+        LUN information:
+            LUN: 0
+                Type: controller
+                SCSI ID: IET     00010000
+                SCSI SN: beaf10
+                Size: 0 MB, Block size: 1
+                Online: Yes
+                Removable media: No
+                Readonly: No
+                Backing store type: null
+                Backing store path: None
+                Backing store flags:
+            LUN: 1
+                Type: disk
+                SCSI ID: IET     00010001
+                SCSI SN: beaf11
+                Size: 8590 MB, Block size: 512
+                Online: Yes
+                Removable media: No
+                Readonly: No
+                Backing store type: rdwr
+                Backing store path: /dev/drbd/by-res/iscsi
+                Backing store flags:
+        Account information:
+        ACL information:
+            ALL
+
+# Connect An Initiator
+
+Install the iscsi utils:
+
+    yum install iscsi-initiator-utils
+    chkconfig iscsi on
+    chkconfig iscsid on
+
+Discover the targets on the host and login to the target.
+
+    iscsiadm -m discovery -t sendtargets -p 10.0.0.101
+    iscsiadm -m node --login
+
+If you run `cat /proc/partitions` you will see an new partition has
+appeared. You can do whatever you want with it.