All for SAN and SAN for ALL!

As Pierre Roman pointed out on April 5th, Microsoft released its Software iSCSI Target to the Download Center (The Microsoft iSCSI Software Target is now free).  I call it The Great Equalizer.  Let me explain:



There are two ways of creating shared storage.

  1. Network Attached Storage (NAS) is file-level storage that you create by formatting a volume on a server (or workstation or NAS device), and then enabling Sharing.  Depending on the type of share you can assign different types of permissions to different users and groups.  You access a share by using a Share Name (formerly called User Principal Name – UPN) such as \\servername\sharename.  If the share was created on a Windows server (or client) you could access the same directory by navigating to the shared location in Windows Explorer.
  2. Storage Area Networks (SANs) are a block-level shared storage, which means they are accessed very differently.  The SAN device is an array of disks that is ‘sliced’ into Logical Unit Numbers (LUNs).  Each LUN is in effect its own hard drive, which is assigned a drive letter (i.e.: M:\) and can be formatted by the computer accessing it (using an iSCSI Initiator).  This gives us options that we could never have with shares… such as NTFS permissions and actually booting servers from a LUN (diskless boot).

There are actually two different SAN technologies in play:

iSCSI (Internet SCSI), which uses familiar RJ-45 cables and communicates over standard TCI/IP networks.  As such all of what we know from basic networking applies, and although it is usually recommended that the storage network be segregated from the production networks, this is often done by using VLAN tags rather than separate NICs (actually referred to as HBAs (Host Bus Adapters) and cables.  By default (for those of you implementing or simply studying for an exam), iSCSI traffic is transmitted on TCP Port 3260.

Fibre Channel (FC) uses proprietary ports, cables, and switches.  Although it essentially speaks the same language (SCSI protocol) it is encapsulated in Fibre Channel packets.  Fibre Channel is usually the more expensive of the two options.

The problem is that neither of these technologies is cheap.  While the investment for an organization has obvious benefits and the ROI is apparent, neither technology is really prevalent in small business because of the cost.  It is very rare that an individual – even an enthusiast – would have a SAN at home.

Does this really affect anyone?  You bet it does. 

  • It affects the guys trying to get into the industry who don’t enrol in a school, but rather try to learn on their own.  They can read all about clustering in books, but until they get their hands on it they will never really know it… and without a SAN they will never really know it. 
  • It affects the IT Pro who have been pigeon-holed in a role and see no possibility for advancement in their organization, and want to take a few certification exams before they update their CV. 
  • It affects the small business IT Pro whose organization hasn’t invested in SANs, but wants to grow into the ‘Enterprise.’
  • It affects anyone who wants to learn virtualization and pass the MCTS exam for Windows Server Virtualization.
  • If you don’t have a SAN that you can play with, it affects you!

Microsoft iSCSI Software Target 3.3  changes all of this. 

  • It allows an IT Pro – anyone, really – can install it on Windows Server 2008 R2 and create a software iSCSI target – essentially a simulated SAN. 
  • It is going to allow us to create clusters in our basements, without investing heavily in hardware. 
  • It means that the youngsters of the industry – our future – can implement and learn Clustering, Live Migration, and all of the other great tools that Windows Server 2008 R2 offers. 
  • Because it is now a supported product from Microsoft, it means that smaller organizations that are interested in virtualization, but scared that it means they are creating a single point of failure if they aren’t able to invest heavily in a SAN device.

In fact, the product is not new… it was released with Windows Storage Server 2008 R2, which was only available through the OEM channel.  Prior to that it was only available internally.  Now that it is being made available widely, it is be supported for (smaller) production environments.

Comments (1)
  1. tony says:

    Thanks, it felt like your wrote this blog for me personally.  I look forward to your follow-up post.

Comments are closed.

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