short stroking

Short stroking is the practice of formatting a disk drive such that data is written only to the outer sectors of the disk's platters.

In I/O-intensive environments, short stroking reduces latency and increases performance because it reduces the time the drive actuator spends seeking sectors on a platter.  The actuator arm, which holds the disk read head, moves across the disk platter in much the same way as a record player arm moves across a vinyl album. Short stroking limits the maximum distance the disk read head can be from any point on the drive by confining the disk read head to the outside edge of the disk.

Short stroking can be used in conjunction with data tiering. In such a scenario, the least important data resides in the middle of the disk, taking longer to fetch, while critical data lives on the outer edges where the robotic arm can reach it more easily. 

Environments that implement short stroking typically have to make up for the reduced capacity utilized in each disk drive by increasing the number of disk drives.  This is not only expensive, it is wasteful. Solid-state storage, which has zero seek time, can be a cost-effective alternative.  For example, if an organization is short stroking hard drives to 25%, it may be more efficient for the organization to purchase one solid state drive instead of 4 mechanical hard drives.  Even if the price of the storage media is comparable, the organization will save on power and cooling.

This was last updated in January 2012

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