The Poor Man's iSCSI SAN
There are a lot of things that go into how to determine what the best storage environment is, whether or not to use SAN vs. NAS, the type of infrastructure, etc., but let's take the goal at face value. 

If you are looking for a more quick-and-dirty setup for building up and tearing down VMs quickly, rather than looking for something with a sense of permanence, then it doesn't have to cost thousands and thousands of dollars (pounds, euros, yen, etc.). Perhaps you may even be looking for something that you can keep in your own home office. 

For someone starting out who wants to get his/her feet wet, there are pretty inexpensive means by which to do this. Here is what my minimum setup would look like:

  • Server: Intel NUC (with a 1G Ethernet port) 
  • Switch: 1G Ethernet Switch (w/ VLAN capabilities; do NOT use wifi for iSCSI!) 
  • Storage: Synology DS918+ or DS1517+ with Western Digital RED drives (I wouldn’t go lower than 4TB drives, with a minimum of 3 of them - do NOT use “green” drives under any circumstances)
  • Cabling: Cat5e (not Cat5) or Cat 6
  • Software (free!) iSCSI initiator

Out the door, you’re looking at an entire setup for less than $2k. 

The Technical Bits

The Intel NUC is your server and for personal virtualization and software development work is, believe it or not, overkill. I have a series of NUCs in my home lab that are running vSphere 6.5 with VSAN and I have yet to make it flinch. At all.

You’ll need and want a managed switch that has VLAN capabilities (iSCSI traffic should be isolated on its own VLAN, and it’s a good idea to get in the habit of setting up your storage network correctly to avoid Bad Things™). You may already have this capability in your existing Ethernet switch at home, so check the user manual. 

Don’t worry about link aggregation, active/active or active/passive failover, jumbo frames, QoS, or other networking tricks. For this setup it’s not worth it, and you will likely never see any benefits for what you are going to be doing. 

Do not attempt to run block storage over wifi. Just. Don’t. Do. It.

The Synology systems have built-in iSCSI software, without the need for licenses or complex setups. In fact, by comparison, it’s so easy that you will have things up and running in less than ten minutes on the storage side.

Even though the Synology is a NAS (network attached storage), the iSCSI volumes it creates are block, which mean you can create a poor-man’s SAN using the device. Depending upon how many server instances/VMs you are going to be using, either one of the options I’ve listed above will do just fine. 

You want a minimum of three drives in a minimum RAID 5 configuration. That may affect your buying decisions. You cannot do RAID 5 with 1 or 2 drives - it must be a minimum of 3. 

The drives you use will make a huge difference. Given the nature of the enclosures and use cases for the type of block storage you are talking about, I (personally) would not even consider anything lower than a 4TB RED drive. You have budget options and performance options, and you can determine which is best for your situation. You should note that if capacity is going to be an issue, that the budget 6TB RED drive is cheaper than the performance 4TB. 

Don't forget the cabling: don’t do everything right with the equipment and then chintz out on the cables. Do yourself a favor and get new Cat5e or Cat6 cabling. The cables you’ve got sitting in a cardboard box in the back of your closet or in your garage will do you no favors for iSCSI traffic. They’re cheap, and it’s just not worth the headache of using old leftovers.

Finally, depending on your OS and hypervisor (VirtualBox is quite popular now as it’s free), most of the basic material to get started is either included or freely available for download. 

Bottom Line

One of the reasons why iSCSI is so popular, both in and out of data centers, is that it does not require massive amounts of investment. It runs on common hardware, and most of the available software is free. 

Even so, you want to make sure you aren’t spending most of your time fixing hardware or fiddling with the infrastructure. If you’re looking for a basic home lab for virtualization, containers, or software development, you’ll likely be wanting to be spending your time on virtualization, containers, or software development (and not getting the equipment to work). 

For many people, $2k is a pretty big investment in any case, but the big part of that cost is going to be the iSCSI storage capability, and there really isn’t any way around that. One of the things you learn very quickly is that block storage has a baseline entry cost because of its rather unforgiving nature

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