Acomdata PHD320UHE-54 External Hard Drive PHD320UHE-54 用户手册



A hard drive is a very sophisticated and sensitive device that

requires proper care and maintenance to ensure the longest

possible life, reliable operation and—most importantly—

the integrity of your stored data.

A hard drive stores data on disks called platters. Each platter

surface is divided into concentric tracks. Each track is divided

into sectors. A group of sectors, called a cluster, or allocation 

unit, is the smallest unit of data storage space.
When data is saved to a new hard drive, it is written to

disk contiguously, one cluster after another. As old files

are erased, clusters that were previously occupied become

available for new data. However, there may not be enough

space for the drive to write a new file in a contiguous set

of clusters. The drive uses the clusters it can; if more are

needed it searches for empty clusters in other locations on

the disk(s). The result is a fragmented file.
Over time, as old files are erased and new files are writ-

ten, the data becomes increasingly fragmented. The more

fragmented a disk becomes, the longer it takes to read