Month: August 2014

Storage industry transition

Storage industry will be transitioning to 4,096-byte sectors

The data storage industry will be transitioning the physical format of hard disk drives from 512-byte sectors to 4,096-byte sectors in the near future. There are a couple of reasons for this increase: drive size and reliability.

This transition causes incompatibility issues with existing software, including operating systems and applications. More information about using large sector drives with Windows is available from the following KB article:

Older, 512-byte-sector drives require quite a bit of space just to store the error-correcting code (ECC) for each sector. The ECC section contains codes that are used to repair and recover data that might be damaged during the reading or writing process.

The legacy sector format contains a Gap section, a Sync section, an Address Mark section, a Data section, and an ECC section (see Figure).

As drive manufacturers are increasing the amount of data that can be stuffed into an area, which is called the areal density, the signal-to-noise ratio (SNR) is adversely affected. The lower the ratio, the more drive space must be given up to ECC. At a certain point, any gain made in areal density is almost lost to additional ECC.

Going forward to drives with 4K sectors, the ECC used for a single sector is significantly less than it would be for eight 512-byte sectors. In other words, the less space used for ECC, the more space can be used to store real data.