The Physical Challenges of Disk Defragmentation in an Emerging VMware World

In the computer industry, Diskeeeper is as synonymous with disk defragmentation as Microsoft is to Windows. In fact, any knowledgeable Microsoft Windows administrator knows that defragmenting a disk drive can provide application performance boosts of up to 176 percent, if you believe some reports. That makes Diskeeper a must-have in the eyes of some shops with performance intensive applications running on Windows servers. However as more enterprises virtualize their servers and disk drives, how does Diskeeper’s technology remain relevant? To get some answers to these questions, I recently spoke to Derek De Vette, VP of Public Affairs for Diskeeper Corporation.

De Vette acknowledges that at the enterprise level, server virtualization is just shy of becoming a mandate. While Diskeeper is already certified with both Microsoft’s Hyper-V and VMware ESX server, there are substantial differences between how Diskeeper performs on these systems with these differences going to the core of how these two server virtualization products are architected.

At a high level, Microsoft Hyper-V preserves the standard logical volume and disk formats that Windows administrators know and understand. Conversely, the VMware ESX hypervisor uses a file system and treats each virtual machine (VM) as a file, referred to as a vmdk file, that is managed by the ESX hypervisor file system.

The vmdk files present unique challenges for defragmentation on a number of levels. Once servers are virtualized using VMware, they no longer have access to specific disk drives or sectors on a disk drive but all of the information associated with a VM is now stored on its vmdk file. While VMware ESX does make some provisions for raw device mappings so guest VMs can access raw or native disk drives, this is the exception not the rule when implementing VMs and certainly not one that the majority of enterprises are prone to use.

If anything, the number of places where defragmentation can occur increases once virtualization is implemented. De Vette points out that defragmentation can occur on the vmdk image associated with the VM, at the VMware hypervisor level and on the indexes used by VMware to track the physical-to-logical mappings. As a result, the complexity associated with defragmenting virtual disks at these different levels also increases because if you defragment the vmdk file, it can possibly undo the benefits gained when defragmenting at the hypervisor level and vice versa. Given that Diskeeper does not operate on the ESX platform, this will be a challenge that they need to address in the future. They will also need to offer means to defragment the indexes associated with the VMware ESX server with that technology.

That does not mean Diskeeper is not aware of these challenges as it is taking steps to address them. De Vette acknowledges that Diskeeper is in regular contact with VMware and looking to more tightly integrate with its ESX server so it can continue to provide the same value it provides now in Windows environments. Further, Diskeeper has seen the Linux market stabilize in its distributions so that major revisions and updates to the Linux operating system only occur about once every 18 months rather than haphazardly, as has sometimes occurred in the past. While Linux and VMware are not necessarily inextricably linked, a stabilizing Linux platform coupled with the controlled development of VMware ESX bodes well for Diskeeper to port its technology to one or both of these platforms at sometime in the future with VMware ESX the obvious first choice.

The corporate adoption of server virtualization in general and VMware in particular presents an ongoing challenge for Diskeeper. While I would not expect it to have significant problems in adapting to server virtualization technologies such as Microsoft Hyper-V, VMware is a whole new bailiwick and does not play well to Diskeeper’s historical strengths. Diskeeper has strong ties with Microsoft Windows but with VMware ESX rooted in Linux, not only does Diskeeper need to adapt its technology to Linux, it needs to concurrently adjust its technology to the subtleties of Linux, VMware ESX and guest operating systems at the same time.

Diskeeper is admittedly the de facto industry standard for disk defragmentation and holds the pole position. But its tight allegiance to Windows has opened an opportunity for competitors, especially if the enterprise space goes virtual using VMware. If that occurs, Diskeeper is under the gun to adapt to the new reality of VMware and quickly figure out how to best address the complexities that defragmenting disk drives in a VMware virtual world presents. But the fact that it has no serious competitors in this space and is proactively working with VMware more than likely translates into Diskeeper providing a robust VMware solution sometime in the near future.

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