This article can also be found in the Premium Editorial Download "Storage magazine: Expanding SANs: How to scale today's storage networks."
Download it now to read this article plus other related content.
Defragmenting your disks is a lot like flossing your teeth: Both are great preventative measures that are often neglected until it's too late. A server full of fragmented files--like a mouth full of cavities--can be painful to fix.
Yet for many storage managers, disk defragmentation--the process of rearranging fragmented files so empty storage spaces can be reused--has been "lost in the shuffle of priorities," says Laura Didio, a senior analyst at The Yankee Group, Boston, MA.
"It's been overlooked as a housekeeping chore," says Didio. "If you're a CTO and your budget's been slashed, you say: 'I can get by without defragging.' But you're only putting off inevitable problems."
Those problems can range from downtime because of application errors to an outright crash, not to mention man hours spent on troubleshooting slow servers, increased calls to the help desk and possibly even buying new hardware, says Didio.
"Even a moderately fragmented server can chip away at performance," says Bob Nolan, president and CEO of Raxco Software, Gaithersburg, MD, maker of disk defragmenter PerfectDisk. "Defragging may only improve the time it takes a file to open from five seconds to two seconds. But that's 60% improvement. You're paying people to wait for files to open and it's going to take longer and longer if you don't defrag."
The reason most storage managers do not regularly defrag their servers, says Nolan, is that servers need to be available 24/7, and
Darryl Brooks, a Brocade Certified storage area network (SAN) designer and principal storage architect concurs that defragging is essential for administrators managing the most performance-sensitive applications, but he says that "with today's 15K rpm drives combined with Fibre Channel (FC) SANs, the speed of these entities seem to mask the problems that arise from a fragmented file system."
Brooks also agrees that lack of time is why storage administrators may bypass defragging. "Unless they have purchased third-party software that permits them to defrag a file system during its off-peak time--but while it is mounted--the application will incur downtime. And that's a bad word in our world," he says.
Nolan, however, sees defrag as a sacrifice that pays off in less downtime later. "Backups will keep taking longer until you have to look at a solution," he says. "In the time it takes to defrag, you will save hours on each backup cycle." --Shane O'Neill
This was first published in November 2003