Upgraded Storage Standard Causes Headaches

Server Technology Hits A Crossroads

New disk drive systems coming out with 4-kilobyte storage sectors, replacing the 512-byte standard of old, offer a lot of great advantages, such as increased storage capacity. But the transition is creating a problem for storage system administrators called storage partition misalignment. The problem occurs when new storage based on the 4K standard is installed in IT systems as a replacement for the 512-byte standard. It's as much a problem for virtual storage environments as non-virtual.

A storage industry consultant explained the problem in a webcast this week that was hosted by a software company that says it has an answer to the problem. Paragon Software Group introduced the Migration Suite for Servers, which eases the transfer of system software and data to dissimilar server hardware in data centers. Included is a feature that corrects for storage partition misalignment.

"It's a transition that had to be made," said Thomas Coughlin, founder and president of Coughlin Associates, of the move from 512-byte to 4K sectors. A sector is an individual portion of data that is written to, and later read from, a disk drive. Think of them as bricks laid one after the other, to make a road. The 4K standard improves disk drive capacity by 9%, improves error correction in the header portion of the sectors, and increases recording density necessary for "getting future generations of products to work," Coughlin said.

"But if care isn't taken you can end up with a misalignment between the physical location of the data on the drive and the logical sector information on where drive and the systems using the drive think the data is," he said.

This misalignment means the drive has to work harder to find the data if it's not where the logic thinks it is. That can impede drive performance by 20% to 30% and, in some cases, as much as 50%, Coughlin said.

Misalignment also can increase wear and tear on drives, shortening their life, he added. It especially affects solid-state drives (SSD), though it also affects traditional hard disk drives.

Paragon's system to correct misalignment has been licensed by storage hardware makers such as Dell, HP, and Toshiba, said Daniel Eickhoff, director of channel sales for Paragon.

"It automatically detects and corrects misaligned partitions in a single operation," said Eickhoff. "As a result, it optimizes the performance of disk subsystems and it significantly increases the longevity of drive, most critically with SSDs."

Paragon is not the only company offering partition realignment, Coughlin wrote in a follow-up email. Other providers include Hitachi, Symantec, and Seagate. Storage vendors such as EMC, IBM, and NetApp use third-party software, some focused on Linux operating systems and others focused on Microsoft.

Coughlin said in the webcast that the misalignment problem is greater for pre-Vista Windows operating systems. That poses a particular risk for enterprises because many of them still use the older Windows XP OS because transitioning to the current Windows 7 OS is a much more difficult task for enterprises than it is for consumers.

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