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Another Round with iSCSI and ESX Server 3

There were two driving factors that led me to rebuild the iSCSI-based storage that was currently serving the test lab, instead of continuing to use the Data ONTAP Simulator. First, we had acquired a Gigabit Ethernet backbone for the test lab, and I wasn’t convinced that the Data ONTAP Simulator was taking full advantage of the Gigabit Ethernet NICs I installed in the server. I also wanted to test bonding some NICs together for more throughput, or possibly to try some multipathing. I couldn’t do either of those with the Data ONTAP Simulator. Note that this is not a knock against the Data ONTAP Simulator; it’s not designed or intended for those kinds of things. (It would be great if I could get a real NetApp device in the lab, but I don’t know if that will ever happen.)

After doing some brief research, I settled on using CentOS 4.3 and the iSCSI Enterprise Target (IET). The installation of CentOS was straightforward and simple, and the installation of IET was equally simple, due perhaps to these fairly detailed instructions for installation of RHEL 4 (which are equally applicable to CentOS 4). I heartily recommend, based on my experience so far, using the source RPMs instead of building from source. It made the process easy and (almost) painless.

I setup a 10GB logical volume using LVM2 and configured IET to present it via iSCSI by editing /etc/ietd.conf to show this:

    IncomingUser isanuser secretpw
    Lun 0 Path=/dev/VolGroup00/lvol0,Type=fileio

(Obviously, you’d need to adjust this as appropriate for your own installation.)

Having already learned my lesson regarding the ESX firewall, I ensured that the software iSCSI initiator traffic was allowed outbound before continuing (refer here for more details). Using the Virtual Infrastructure client, I reconfigured the ESX 3 server to see the new iSCSI server, and the new LUN popped up immediately upon a rescan. From there, it was a simple operation to establish a new VMFS datastore on the iSCSI LUN and move a VM to the LUN. That was easy!

The next steps will be to do some performance tuning, test bonding the NICs and/or multipathing, and perform some NFS interoperability tests. (Remember that NFS is also supported by ESX 3 for datastores.)

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