Don’t Let Fragmentation Add to SAN Complexity

Storage Area Networks (SANs) are a great boon to enterprises everywhere. Because a SAN removes network traffic from the production system, network traffic is freed up to accommodate day-to-day operations—themselves a heavy load. SANs generally implement multiple physical disk drives in some form of fault tolerant disk striping (RAID), and do provide a great benefit to an enterprise: because stored data does not reside directly on any of a network's servers, server power is utilized for business applications and network capacity is released to the end user.

Connecting a machine to a SAN has always been a bit of a task—it normally has to be performed manually, and with today’s heterogeneous environments there has to be considerable know-how involved in the machine’s interaction with the SAN. It becomes even more complicated, however, with the advent of virtual machines (VMs)—for each VM, a “relationship” must be established with the SAN. Since VMs can now be created and deleted on-the-fly by the users themselves, automated solutions are now appearing that will allow VMs to be automatically connected. Whether this will be a workable solution or not remains to be seen, but obviously something needs to happen to make this operation efficient.

File fragmentation already negatively affects SAN performance, if not fully addressed with an automatic solution. Physical members in a SAN environment are not read or written to directly by an application, but instead are “seen” by an application and even the OS as one single “logical” drive. When an I/O request is processed by the file system, there are a number of attributes that must be checked which cost valuable system time. If an application has to issue multiple "unnecessary" I/O requests, as in the case of fragmentation, not only is the processor kept busier than needed, but once the I/O request has been issued, the RAID hardware and software must process it and determine to which physical member the I/O request must be directed. When files are fragmented into hundreds, thousands or tens of thousands of fragments (not at all uncommon), there are obviously many more extra I/O requests. Performance slows to a crawl.

With all that must be done to keep a SAN up and running and to ensure all machines and applications are connected, IT personnel cannot afford to be chasing down and addressing symptoms of file fragmentation. Especially with the addition of VMs, there is already enough to do. Fragmentation must be constantly addressed so that is simply eliminated—a task that can only be performed with a fully automatic solution. Such a solution works invisibly, in the background, with no negative impact on system processes and—best of all—no required scheduling by IT personnel.

Don’t let fragmentation add to SAN complexity. Make sure your fragmentation solution allows you to address factors that truly need addressing.

The Right Defrag Solution--More Cost Effective Than a Free Solution

A utility or function that is "free" should always be examined carefully. For example, an aspiring musician may go shopping for a keyboard and find one for a decent price that has a built-in "free" drum machine. On the surface, it sounds like a great deal; they can have rhythm accompaniment as they play and it's like having your own little band. But when they get the keyboard home and actually put this "free" drum machine to work, they find that it's very limited in the sounds it will produce and in fact makes their creations sound a bit cheesy. In order to make it sound halfway good, the drum sounds will have to be run through a separate amplifier. But then they find that they can't even run the drum machine out from the keyboard separately. After countless wasted hours and endless tweaking, the musician realizes that it would have taken far less money and time—and would have produced a better result—if he or she had just invested in a professional drum machine in the first place.

Moving over into the world of computers, one finds a similar scenario: that of a free defragmenter. Again on the surface it sounds ideal. There is no up-front cost, and it will take care of that performance-crippling fragmentation problem so IT can take their attention off of it and move onto other pressing matters.

But when the time comes to actually get the defragmentation work done, a realization will dawn upon the system administrator about how “free” this defrag solution isn’t. First it has to be scheduled, many times on systems that must remain up and running 24X7. Many IT hours can be wasted in trying to fit in such schedules. Users cannot be on the system when the free defrag is running, causing more lost time and worse, income. And in between these scheduled runs, fragmentation continues to build and impact performance and reliability, which lowers the cost-effectiveness of the entire enterprise.

Then even more problems arise. IT personnel can never tell if a disk is fully defragged because there is no progress chart in the UI. Only one instance of the defragger can be run at a time. Only local drives can be defragmented.

The only true defrag solution today is one that does not require scheduling and addresses fragmentation consistently in the background. Because only idle system resources are used, there is never a negative impact on users. Such a solution means that IT can remove their attention from fragmentation at the moment this solution is installed—performance and reliability are constantly maximized. When comparing such a solution to the free defragmenter, the actual and staggering costs of the "free" utility become readily apparent.

When "Free" Actually Costs More

This might have happened to you: You’re off on a resort vacation that you’ve looked forward to for months, in some tropical paradise. You’re dreamily exploring the resort on the first day, and you come across a person who offers you a free champagne brunch, for you and your spouse. You think, great! A free high-end meal! When you get there, though, you realize how free it isn’t. The food is great—but you have to sit there for two hours listening to a sales pitch on condo timesharing. And for the rest of your vacation, some salesman is pursuing you all over the resort, popping up every time you turn around, trying to close you on buying into his "great plan." That "free brunch" was anything but—it put a serious damper in your dream vacation, which you paid substantial money to take.

In the world of computing, the same could be said for a free or inexpensive defrag utility. Yes, it costs little to nothing at the outset—but defragmentation is a serious performance problem, and soon you’re going to have to run that utility. The first problem you’re going to have is, it needs to be scheduled. Most corporate systems need to be up and running constantly, so finding a time window in which to schedule defragmentation is a major problem. And, the time that the system is offline is the first major cost of the free or inexpensive utility.

When you finally can schedule and run it, you find out that it runs, and runs, and runs, consuming system resources the whole while, and never seems to actually complete a defrag job. If you add up the number of hours that IT staff have spent trying to get useful work out of this utility, you’ll come across the second major cost of this utility.

There are third-party solutions to fragmentation that are far more efficient. In fact, technology has now evolved to the point that a majority of fragmentation can actually be prevented before it even occurs—completely automatically, and with no impact on system resources. The I/O resources required to defragment files after they have already been fragmented are saved, and peak performance is constantly maintained.

Now, compare the price of the of the free or "low-cost" utility to the third-party solution. There is an initial cost for the third-party solution—but once it is installed and running, fragmentation is basically a thing of the past. The net result: the bargain utility actually costs far more.