Differences between version 5 and predecessor to the previous major change of LBA.
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| Newer page: | version 5 | Last edited on Sunday, September 26, 2004 8:49:00 pm | by AristotlePagaltzis | Revert |
| Older page: | version 4 | Last edited on Sunday, September 26, 2004 7:29:27 pm | by DanielLawson | Revert |
@@ -1,30 +1,32 @@
An Acronym for __L__ogical __B__lock __A__ddressing
-[LBA] gives
sectors a linear
number starting with
, as opposed to
the classic cylinder-head-sector (
CHS)
addressing.
+[LBA] is a addressing scheme for HardDisk
sectors that uses
a single
number starting at
. It supersedes
the classic [
CHS]
addressing.
-LBA addresses can be 28 bit or 48 bit wide. If your disk has 512 byte sectors (fairly common), a 28 bit LBA device can address 128 GB of disk. Here's the maths:
+[
LBA]
addresses can be 28 bit or 48 bit wide.
-<verbatim>
-sectors = 2^9 Bytes.
-1 GB = 2 ^ 30 Bytes.
+With the common
512 byte sector size, 28 bits are somewhat limiting:''''
-2 ^ 28 * 2 ^ 9 Bytes
= 2 ^ 37 Bytes = 137438953472 Bytes
-2 ^ 37 Bytes / 2 ^ 30 = 2 ^ 7 GB = 128 GB
-verbatim
>
+ 512 byte sectors
= 2<sup>9
</sup
> Bytes
-Disk manufacturers actually use GiB (10^9, as opposed to 1024^3):
-verbatim
>
-^ 37 bytes = 137438953472
Bytes = 137.43 GiB
-verbatim
>
+ 2
<sup
>28</sup> *
2<sup>9</sup>
Bytes = 2<sup>37
</sup
> Bytes = 137,438,953,472 Bytes
-This
is the reason for older OS
's or controllers failing to detect a large disk correctly.
+That
is 128[GiB]:'''
'
-48 bit LBA offers much larger disks:
+ 1 [GiB] = 2<sup>30</sup> Bytes
-<verbatim
>
-2 ^ 48 * 2 ^ 9
Bytes / 2 ^
30 = 2 ^ 27 GB = 134217728 GB = 128 EB
-verbatim
>
+ 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
+
+----
Part of CategoryHardware
