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Linux on 4KB-sector disks: Practical advice

Apr 28, 2010, 17:33 (0 Talkback[s])
(Other stories by Roderick W. Smith)

"Why change to 4096-byte sectors?

"If you're familiar with disk structure, you know that disks are broken down into sectors, which are normally 512 bytes in size; all read or write operations occur in multiples of the sector size. When you look closer, hard disks actually include a great deal of extra data in between sectors. These extra bytes are used by the disk's firmware to detect and correct errors within each sector. As hard disks grow larger, the result is that more and more data must be stored on each square centimeter of disk, resulting in more low-level errors, thus straining the firmware's error correction capabilities.

"One way around this problem is to increase the sector size from 512 bytes to a larger value, enabling more powerful error-correction algorithms to be used. These algorithms can use less data on a per-byte basis to correct for more serious problems than is possible with 512-byte sectors. Thus, changing to a larger sector size has two practical benefits: improved reliability and greater disk capacity—at least in theory.

"The real-world benefits to end users aren't likely to be obvious in the same way that an increased monitor size or improved central processing unit (CPU) speed are obvious. However, the reduction in space devoted to parity may result in quicker introduction of larger disks or better disk reliability."

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