NSS4000 Gigabit 4Bay Chassis

Linksys / Cisco have a serious contender here for the small business community needing a quick easy storage solution to throw into their network.

The flexiibility to optimize the NSS4000 for capacity and sharing is not to be taken lightly.  Sadly – the limiting facter is 15 concurrent users – but as a network shared storage it works well. The feature set of the NSS series set it apart from entry-level, desktop NAS systems, while at the same time its competitive pricing gives small businesses the opportunity to realize substantial cost savings when compared with more expensive storage systems.

Unlike other NAS systems, that need to contain operating system software on one or more hard drives in a NAS system, the NSS400 contains the Linux OS that controls it on board. This gives the NSS system added stability and reliability, as well as the flexibility to be configured without connected drives or reconfigured at any time – even hot swapping and resorting hard drives to different storage bays.

If you are serious about needing an entry level NAS and do not want to go opensource – this should be one for you to review.  Go with one suggestion however – grab the empty chassis and add your own drives.   We have 4 2TB drives running our testing environment – something not even sold off the Linksys shelf – sadly the 150M limit on SATA vs SATAII did bog us down a little.

Nowadays, the iSCSI technology is quite popular in the storage world

Running iSCSI target on a Fedora system is as easy as “yum install iscsitarget” and configure the thing.

On CentOS – however  iSCSI Enterprise Target (IET) daemon is not in the default Yum repositories – and while CentOS does offer TGT  (Linux SCSI Target Framework) I think for a SAN – IET is best.

In short – this requires us to start from scratch – and build from source.  It is important to note – whenever you update your kernel – you will need to recompile.

The iSCSI Target system

First, some prerequisites :

# yum install openssl-devel kernel-dev gcc rpm-build

Download the latest IET from the Sourceforge repo and put the tgz in /usr/src

# cd /usr/src
# tar xvf iscsitarget-0.4.17.tar.gz
# cd iscsitarget-0.4.17
# make
# make install

Like most everything in linux – now that the make install is complete – your ready to go (except a minor configuration of course).  The iscsi-target init.d script is installed and will be started at boot-time.

Configuring the ietd host is pretty simple and the WIKI has tons of valuable information.
First, lets decide who can connect to the IET daemon :

First you have to have a naming convention for your IQN (iScsi Qualified Name) -   The IQN is an identifier for your iSCSI target.

Ok – so glenn – what the heck is this needed for? – I’m glad you asked..   The iSCSI initiator using the IQN to connect to the disks/lun’s.

# nano /etc/initiators.allow

iqn.namingconvension:mydiskname 10.0.100.0/24

In the above example The subnet 10.0.100.0/24 is allowed to use this iSCSI target.

Next, we’ll create the initiators.deny file, which is pretty straightforward :

 # nano /etc/initiators.deny

ALL:ALL

Time to create the IQN in the ietd configuration file.

# nano /etc/ietd.conf

Target
iqn.namingconvension:mydiskname
IncomingUser username 12345
OutgoingUser username 123456789012
Lun 0 Path=/dev/SAN/diskname,Type=fileio,IOMode=wb
Alias iSCSI for diskname
ImmediateData Yes
MaxConnections 1
InitialR2T Yes

I use the following conventions, as defined in the RFC :

For IncomingUser: Password always 5 characters
For OutgoingUser: Password always 12 characters

I suggest using LVM as a disk backend. The disk can also be /dev/sdb or whatever your heart desires…

The iSCSI Initiator

In Ubuntu/Debian/Fedora/ (or pick your Nix version and place here) there usually is an open-iscsi in the repository. If not, you can always compile it from source at http://www.open-iscsi.org.

I love the CentOS Nix version – so the directions below – are assuming you have a CentOS system you would like to use with your new san.

Let’s install the prerequisites :

# yum install iscsi-initiator-utils
# yum install open-iscsi

Next, define the initiator name. This is in the exact same form as the target name, but it should not be the same. This initiator name is the name (in IQN) of your computer.

# nano /etc/iscsi/initiatorname.iscsi

InitiatorName=iqn.namingconvension:someuniquename

Next, we’re going to configure the authentication and some specials in the iscsid config.

# nano /etc/iscsi/iscsid.conf

node.startup = automatic
node.session.auth.authmethod = CHAP
node.session.auth.username = username
node.session.auth.password = 12345
node.session.auth.username_in = username
node.session.auth.password_in = 123456789012
node.session.timeo.replacement_timeout = 120
node.conn[0].timeo.login_timeout = 15
node.conn[0].timeo.logout_timeout = 15
node.conn[0].timeo.noop_out_interval = 10
node.conn[0].timeo.noop_out_timeout = 15
node.session.initial_login_retry_max = 10
node.session.cmds_max = 128
node.session.queue_depth = 32
node.session.iscsi.InitialR2T = No
node.session.iscsi.ImmediateData = Yes
node.session.iscsi.FirstBurstLength = 262144
node.session.iscsi.MaxBurstLength = 16776192
node.conn[0].iscsi.MaxRecvDataSegmentLength = 131072
discovery.sendtargets.iscsi.MaxRecvDataSegmentLength = 32768
node.session.iscsi.FastAbort = No

For more information about these setting, please refer to the open-iscsi page.
Next up, start the thing :

# service iscsi start

Bingo! You just started the iSCSI daemon (all cheer).

Now, we’re going to discover our targets on the target iSCSI host. I assume 10.0.100.1 is the target host in this example.

# iscsiadm -m discovery -t st -p 10.0.100.1
10.0.100.1:3260,1 iqn.namingconvension:mydiskname

As you can see, it found the target we created before. Now, let’s login to it:

# iscsiadm -m node -p 10.0.100.1  -T iqn.namingconvension:mydiskname --login

Congratulations Chap – if you do dh -alh – or dmesg  you will find a new disk inserted (/dev/sdc or whatever).