Home > Articles, I/O, News > FIBRE CHANNEL vs. iSCSI for SQL databases

FIBRE CHANNEL vs. iSCSI for SQL databases


During last several years we saw a lot of battles around Storage Area Network technologies. The largest question there was which technology is better. If you know the answer, send me an email right now because I think it is impossible to have only one right answer thus different business requirements demand different characteristics from SAN.

In this post we are talking about databases (SQL Server, Oracle, DB2, whatever) and everything which relate to them in terms of Storage Area Network technologies. As a result, it is evidently known that the most important characteristic which relates to such an area is performance. To be more precise, performance consists of wide bandwidth and low latency which together allow your database server to perform as fast as it is possible.

Fibre Chanel, which is the oldest technology in contemporary network storage systems, can deliver all the characteristics mentioned above. As a consequence, it became the most popular among highly loaded and critically important databases. The main advantage of this technology is the ability of FC protocol to provide guaranteed delivery of packages, which allows utilizing it as a highly available solution.

One of the alternative technologies is iSCSI. Essentially, iSCSI utilizes Ethernet as a foundation for itself for data transmission. Frankly speaking, it is a good idea because Ethernet is available everywhere, it is cheap, easy to implement, easy to manage and much more affordable than Fibre Channel. Additionally, it utilizes universal network infrastructure, which is very important for businesses from the cost perspective. But, unfortunately, it does not have even comparable performance as Fibre Chanel. As a result, iSCSI could be utilized just for not performance critical solution such as file-servers, mail-servers, etc. Moreover, iSCSI is susceptible to delayed packet transfers or even packet loss. Even if we utilize 10 GB Ethernet it does not help at all. So it is important to consider individual application latency requirements. Consequently, speaking about the database area, we can clearly see that this technology is slow for such purposes.

As a next stage of evolving of SAN technology was Fibre Chanel over Ethernet (FCoE). The idea is slightly different here – utilization of Ethernet infrastructure but consuming FC protocol to guaranty delivery as it was implemented in original Fibre Chanel. This technology can deliver almost the same features as FC. New 10GB Ethernet, which emerged several years ago, promises to reinforce FCoE position on the market providing wide bandwidth as a firm foundation for FCoE. Maybe one of the most important features of FCoE is the ability to work on the same hardware with iSCSI at the same time. Exactly this feature is very important from a global perspective of infrastructure consolidation which contemporary businesses really concern about. FCoE can be used for almost any types of sophisticated features such as remote replication, building distributed environment, etc. But it is also not the former characteristics which are necessary for SQL databases. As a result, we can utilize FCoE as a supplementary technology to provide some more functionality.

We know that that the reason to chose one of the available SAN technologies consist of:

  • Each technology has its place
  • Cost and complexity
  • Technology lock-in

As a result, each CIO, DBA or another technical specialist should decide what is the most important for him.

Taking into account everything mentioned above, we can conclude that it is not fear to dispute which technology is better. Thus, if some company is looking for SAN solution with a balance between price, features and speed we can compare all of them. Otherwise, we evidently know that Fibre Chanel is the fastest and the most reliable but expensive technology ever seen to store data and iSCSI is the cheapest technology but the slowest one.

In order to combine all positive sides from all technologies it would be better to choose network fabrics which can support Fibre Chanel and iSCSI at a time to avoid looking in particular technology and benefit from both of them. SANs that offer simultaneous support for iSCSI and Fibre Channel server connections allow businesses to optimize their storage resources, selecting the right technology for each application, balance performance and
cost, and avoid unnecessary technology lock-in.

Simply speaking, you should have the freedom to choose based on your specific application needs and technology preferences. Nevertheless, do not forget the most critical characteristics of SQL databases which relate to selection of your future SAN technology.

Source: Compellent (http://viewer.media.bitpipe.com)

Reference: Aleksey Fomchenko (https://sqlconsulting.wordpress.com)

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Categories: Articles, I/O, News Tags: , ,
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