Well this isn’t necessarily an easy question to answer. They both have their advantages and disadvantages. Here are my thoughts on the matter.

iSCSI is great for cheap storage, and allows you to get it up and running quickly in your environment, especially if you already have the data switch infrastructure to support it. All you have to do is section off a part of your network for it and you’re good to go. The downside? Your storage network is on your data network. This can cause interesting performance issues if things are configured correctly.

FC is a different story. It has it’s own fabric that is separate from the data network. Because of this the data network doesn’t impede it and it can run happily on it’s own. The downside? FC is usually more expensive and you also have to buy FC switches to accomodate your FC storage. FC is super fast, but at a price.

Generally the farther into the enterprise you roam, the more likely you are to see FC for mission critical apps and data and iSCSI for second tier backups or non-mission critical apps and data. There are exceptions to this however, for example some people will run separate data switches just for iSCSI so the two networks don’t cross.

-RP

Well you might see this term thrown about not just with VMware but with SANs as well. In the simplest of terms, thin provisioning is the act of over-allocating storage. Thin provisioning is a feature provided for you in VMware but it is also provided in many SAN products natively.

Here is an example. Let’s say you have 1 TB of space left on your SAN and you get a few customer requests for allocating some new virtual servers in the environment. The total sum of all the disks you need might exceed the 1 TB you have left. How do you deal with this? When you create the disks, you create them as “thin” instead of “thick”. So let’s say you need to create a 500 GB data drive. But you know that the customer will not use up that whole 500 GB drive for at least a year. All you have to do is create the drive as thin and then the drive will only actually use up the space that is actually used instead of the whole 500 GB. So if there is 50 GB’s of data on the drive, that is the actual size of the disk. This way you have plenty of time to go out and shop around to get the storage you want down the road. You don’t need it up front.

What are the disadvantages? If you forget to add more disk before you run out of storage then you can end up crashing your environment. Not good! Also with thin provisioning you can run into performance issues. I tend to reserve thin provisioning for non-critical items in my environment.

-RP

One of the great things about storage is that there are so many different options. You can go direct attached, FC, NAS, NFS or even iSCSI. I really like iSCSI it’s great for the SMB and it’s great for secondary storage. It’s one of those options that can provide you with lots of bang for your buck.

Well one of the first options I wanted to talk to you about is Starwind iSCSI SAN Storage software. There is a free product that you can try out, and also a fully functional 30 day trial as well. I’ve trialing it for the past little while and I have to say it’s a nice product.

In a nut shell, you can take the software and install it on a Windows box (even a workstation) and then point it at any of your disks (even external USB drives) and then mount them as iSCSI storage! Now I know there are a lot of free options out there but there is something to be said about a pay for product with features such as thin provisioning, remote replication and automatic failover!

If the pay for model isn’t your thing then I urge you to check out FreeNAS and Openfiler!

-RP

I have always been a proponent of usings Blades in the SMB along with virtualization to reduce costs for the SMB. But what do you do for storage? Well the most common thing people look at is iSCSI vs FC. Usually people end up going the iSCSI route due to it’s lower cost factor.

Well another thing you can look at is direct attached storage. HP offers something called Direct Connect SAS storage for their HP BladeSystem. This can give you up to 420 TB of zoned or up to 192 TB of shared storage. This can be an attractive alternative for the SMB.

The way it works is by use of controllers installed in the blade severs along with blade switch interconnects and then finally either an MSA2000sa for shared storage or an MDS600 for direct attached storage. You can read more about the solution from HP here.

-RP