View Source: LBA - Waikato Linux Users Group

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An Acronym for __L__ogical __B__lock __A__ddressing

[LBA] is a addressing scheme for HardDisk sectors that uses a single number starting at 0. It supersedes the classic [CHS] addressing.

[LBA] addresses can be 28 bit or 48 bit wide.

With the common 512 byte sector size, 28 bits are somewhat limiting:''''

    512 byte sectors = 2<sup>9</sup> Bytes

    2<sup>28</sup> * 2<sup>9</sup> Bytes = 2<sup>37</sup> Bytes = 137,438,953,472 Bytes

That is 128[GiB]:''''

    1 [GiB] = 2<sup>30</sup> Bytes

    2<sup>37</sup> Bytes / 2<sup>30</sup> = 2<sup>7</sup> [GiB] = 128 [GiB]

Disk manufacturers actually use [GB], btw:''''

    1 [GB] = 10<sup>9</sup> Bytes

    2<sup>37</sup> Bytes / 10<sup>9</sup> = 137.43 [GB]

This is the reason for older OperatingSystem~s or controllers without 48 bit [LBA] support failing to detect a large contemporary disk correctly.

48 bit [LBA] offers much larger disks:''''

    2<sup>48</sup> * 2<sup>9</sup> Bytes / 2<sup>30</sup> = 2<sup>27</sup> [GiB] = 134,217,728 [GiB] = 128 EB

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Part of CategoryHardware

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Last edited on Sunday, September 26, 2004 8:49:00 pm by AristotlePagaltzis

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