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.

Fully Automatic Defrag for the Most Effective SANs

The late comedian George Carlin used to do a routine that defined a home as “a place to put your stuff.” As it unfolded, the bit talked about the increasing accumulation of “stuff” and how eventually one needed to purchase a bigger home because one had “more stuff.”

The amount of data required by enterprises in order to operate could certainly fall into this humorous category. As computing has become more sophisticated, the volume of “stuff” needed to be kept and analyzed has grown dramatically, and so has the problem of efficiently storing and accessing it all. Storage Area Networks (SANs) solved the problem of isolated storage arrays and their accessibility from all applications; these arrays are networked together in such a way that the entire SAN is viewed as a series of “virtual disk drives,” each easily accessible from anywhere. In addition to access, benefits include simplified administration, scalability and flexibility.

There is one crucial factor that, if not properly and effectively addressed, can however bring SAN efficiency to a crawl, and that is file fragmentation. Since the SAN is “seen” by the OS and applications as logical drives, an I/O request processed by the file system has a number of attributes that must be checked, costing valuable system time. Fragmentation causes an application to issue multiple unnecessary I/O requests, keeping the processor busier than needed. Additionally, once an 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. With all the additional I/O requests, performance is greatly effected.

Today’s data centers are usually up 24X7, and are a terrific hotbed of activity without the added strain of fragmentation. SANs need to be maintained at maximum performance, period; fragmentation must be constantly addressed so that is simply eliminated. The “traditional” approach of scheduling defrag simply won’t work when there are few time windows in which to schedule maintenance—and in between such times fragmentation continues to build and hamper SAN performance.

The only true solution for SAN fragmentation is one that works fully automatically and invisibly, in the background. Because it utilizes only otherwise-idle resources, it requires no scheduling at all and has no negative impact on system processes. Fragmentation is no longer a problem, and SAN performance and reliability are fully maximized.

A SAN is one of the ultimate solutions for an enterprise to store and easily access their “stuff.” Make sure it is always quickly and reliably accessible by choosing the right fragmentation solution from the start.