iSCSI or NFS for an SMB's Virtualized Server Environment: How to Determine Which is Best
As I wrote previously, many small and medium businesses (SMBs) can gain some real benefits from server virtualization with the Iomega StorCenter™ ix4-200d a prime example of a storage appliance that can be used with server virtualization in these environments. But, what I didn't mention was which Ethernet TCP/IP network storage protocol should be used - iSCSI or NFS.
There are several networking options available for running your virtualized server environment. But for the sake of this article, I'm going to stick with the capabilities of the ix4-200d, which are iSCSI and NFS. (NFS is available on the ix4-200d when it is used as a NAS device.)
Existing Experience
iSCSI and NFS are both very good options for use in a virtualized server environment. But, each has its strengths and weaknesses.
iSCSI, a block-based network storage protocol, by itself, is not practical without some sort of front-end device which presents the iSCSI volume for end-users to utilize. Once the volume has been configured on the host, a file system must be created on the iSCSI volume for the storage of your virtual machines. It also adds an additional level of complexity in troubleshooting storage problems that can potentially be masked as network problems. On the upside, iSCSI takes advantage of a company's existing TCP/IP network and can be configured to use multiple network paths to the storage for redundancy.
NFS, which is basically a file-based network protocol, is usable without any sort of front-end device. NFS has been optimized for serving up files and thus makes it a more efficient network storage protocol and, when used in a virtualized server environment, NFS treats each of the virtual guests as a file. On the negative, when used in a virtual infrastructure NFS tends to be a bit slower than iSCSI. This is primarily because of the way NFS has been implemented in the Linux kernel, which VMware's ESX is based upon.
If you have the technical expertise in-house to understand all the complexities that come with using iSCSI and need the performance that iSCSI offers, then going with an iSCSI solution for your virtualized environment is the way to go. However, if you have any concern about using iSCSI, I recommend NFS.
Cost
Cost is another factor that will point you towards the best file protocol choice, assuming most SMBs use an existing IP infrastructure based on an Ethernet networking infrastructure. Both iSCSI and NFS take full advantage of this infrastructure.
If you are planning on virtualizing your entire server environment and using iSCSI then you may want to consider purchasing some iSCSI host bus adapters (HBAs) to help take some of the processing load off of your host CPU. But, each iSCSI HBA can cost up to $1,000 per card which can add another $2,000 in hardware costs if you use two or more cards. It is also considered a best practice to segregate iSCSI traffic from normal network data traffic. To accomplish this requires the creation of another Ethernet network which means additional expense for more cabling and networking gear.
On the other hand, NFS doesn't require any additional software or hardware to get the best performance. All it requires is a fast, 1 gigabit Ethernet network and 1 gigabit network cards in the host servers. Unfortunately, NFS is not a very secure protocol. While this is being remedied in a future version of the protocol, in the meantime you may need to purchase additional hardware such as a firewall, or create virtual LANs (VLANs) for the traffic to traverse.
Whichever protocol you decide to go with know that there is no additional cost when using the ix4-200d. Just purchase the hardware and you're on your way.
Operational Efficiency
Most small IT shops are running thin on technical support personnel so any advantage in operational support that a protocol presents, no matter how small, is welcomed. In this respect, iSCSI runs counter to this. If following best practices and a separate Ethernet network is setup, this creates more overhead and maintenance, not less, plus iSCSI HBAs may need to be installed and configured correctly. Once these two steps are done, then a file system needs to be created on the iSCSI volume before it can be used for storing virtual guests on it.
Conversely, NFS doesn't require any special hardware or software nor does it require a separate network. In addition, it easily integrates with corporate security and authentication domains such as Active Directory and LDAP. This helps to make it more efficient for stretched IT personnel to operate and manage.
Virtualizing your server environment can be an intimidating task, but choosing between iSCSI or NFS can be even more daunting. You need to take in-house expertise, costs and operational efficiency into account when making a decision. For these reasons, I recommend an SMB go with NFS for their virtualized server environment. That doesn't mean that iSCSI should not be used as it is still a great protocol but if security is not a concern, NFS can't be beat for its simplicity and ease of configuration.
There are several networking options available for running your virtualized server environment. But for the sake of this article, I'm going to stick with the capabilities of the ix4-200d, which are iSCSI and NFS. (NFS is available on the ix4-200d when it is used as a NAS device.)
Existing Experience
iSCSI and NFS are both very good options for use in a virtualized server environment. But, each has its strengths and weaknesses.
iSCSI, a block-based network storage protocol, by itself, is not practical without some sort of front-end device which presents the iSCSI volume for end-users to utilize. Once the volume has been configured on the host, a file system must be created on the iSCSI volume for the storage of your virtual machines. It also adds an additional level of complexity in troubleshooting storage problems that can potentially be masked as network problems. On the upside, iSCSI takes advantage of a company's existing TCP/IP network and can be configured to use multiple network paths to the storage for redundancy.
NFS, which is basically a file-based network protocol, is usable without any sort of front-end device. NFS has been optimized for serving up files and thus makes it a more efficient network storage protocol and, when used in a virtualized server environment, NFS treats each of the virtual guests as a file. On the negative, when used in a virtual infrastructure NFS tends to be a bit slower than iSCSI. This is primarily because of the way NFS has been implemented in the Linux kernel, which VMware's ESX is based upon.
If you have the technical expertise in-house to understand all the complexities that come with using iSCSI and need the performance that iSCSI offers, then going with an iSCSI solution for your virtualized environment is the way to go. However, if you have any concern about using iSCSI, I recommend NFS.
Cost
Cost is another factor that will point you towards the best file protocol choice, assuming most SMBs use an existing IP infrastructure based on an Ethernet networking infrastructure. Both iSCSI and NFS take full advantage of this infrastructure.
If you are planning on virtualizing your entire server environment and using iSCSI then you may want to consider purchasing some iSCSI host bus adapters (HBAs) to help take some of the processing load off of your host CPU. But, each iSCSI HBA can cost up to $1,000 per card which can add another $2,000 in hardware costs if you use two or more cards. It is also considered a best practice to segregate iSCSI traffic from normal network data traffic. To accomplish this requires the creation of another Ethernet network which means additional expense for more cabling and networking gear.
On the other hand, NFS doesn't require any additional software or hardware to get the best performance. All it requires is a fast, 1 gigabit Ethernet network and 1 gigabit network cards in the host servers. Unfortunately, NFS is not a very secure protocol. While this is being remedied in a future version of the protocol, in the meantime you may need to purchase additional hardware such as a firewall, or create virtual LANs (VLANs) for the traffic to traverse.
Whichever protocol you decide to go with know that there is no additional cost when using the ix4-200d. Just purchase the hardware and you're on your way.
Operational Efficiency
Most small IT shops are running thin on technical support personnel so any advantage in operational support that a protocol presents, no matter how small, is welcomed. In this respect, iSCSI runs counter to this. If following best practices and a separate Ethernet network is setup, this creates more overhead and maintenance, not less, plus iSCSI HBAs may need to be installed and configured correctly. Once these two steps are done, then a file system needs to be created on the iSCSI volume before it can be used for storing virtual guests on it.
Conversely, NFS doesn't require any special hardware or software nor does it require a separate network. In addition, it easily integrates with corporate security and authentication domains such as Active Directory and LDAP. This helps to make it more efficient for stretched IT personnel to operate and manage.
Virtualizing your server environment can be an intimidating task, but choosing between iSCSI or NFS can be even more daunting. You need to take in-house expertise, costs and operational efficiency into account when making a decision. For these reasons, I recommend an SMB go with NFS for their virtualized server environment. That doesn't mean that iSCSI should not be used as it is still a great protocol but if security is not a concern, NFS can't be beat for its simplicity and ease of configuration.
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