Talk:Logical block addressing

message: Before I took a stab at clarifying the ATA stuff, the article read:
: ...limited to 1024/4096/16384, 16/256 and 63 respectively. Original limits were 1024*16*63, but newer BIOSes can transform a coordinate system with more than 16 (virtual) disk heads into one which has more cylinders instead, or they can transform CHS coordinates in a coordinate system of up to 1024*255*63 size...
This isn't really very clear, as it doesn't say what the circumstances were when 1024/4096/16384 was the max and when 1024/255/63 was.  We should present all the different eras and their corresponding maxes, hopefully with max volume size calculations for each. -- Finlay McWalter |  Talk 23:03, 22 September 2005 (UTC)
thread_title: Ambiguity in ATA maxes, seek advice

message: If Linux (and others) do not use BIOS geometry to determine hard disk size, what does it use? Can we provide an explanation of the alternative scheme?
--64.173.240.130 (talk) 20:49, 18 March 2008 (UTC)
replies: text: I'll attempt to do so at a later date. Essentially they communicate with the hard disks using ATA commands themselves, which is how they can ignore the BIOS code. Daniel B. Sedory (talk) 14:58, 20 March 2008 (UTC)
thread_title:  Ignore BIOS Geometry 

message: For such a simple concept, this topic gets pretty complicated. Besides being an obvious indexing of disk blocks,
LBA refers to specific ATA standards, and its interaction with the coexisting CHS systems.
Besides the 10/8/6 CHS of INT 13H and the DOS MBR, 
the 16/4/8 CHS and 28-bit LBA of ATA-1, and the 48-bit LBA of ATA-6, 
there's a 32 bit LBA in the DOS MBR. There's a lot of history here. 
Ozga (talk) 01:16, 17 November 2009 (UTC)
thread_title:  Complicated topic 

message: I haven't worked with HDDs in many years, so I am out-of-date on much.  However, I am assuming that drives still have occasional bad spots on their platters--and that the drive's internal logic skips over or remaps those spots to previously unallocated spots on the drive.  If so, how is this handled by the drive?  Does it tell the controller outside of the drive that those LBAs are badand thus are not available?  Or does the drive just assign sectors in a previously unallocated area to "assume" the LBAs of the bad sectors--and do all of this transparently to the external controller?
Biscuiteater57 (talk) 13:13, 29 February 2012 (UTC)
replies: text: If implemented, bad sector relocation works transparent inside the drive for both CHS and LBA access. If the drive receives a command to read an unrecoverably bad sector, the drive will return an error, otherwise it will return the sector contents without indicating an error. The operating system could decide to mark those areas affected by detected bad sectors in the file system in order to indicate and handle this on a higher level, but this is left entirely to the implementor of the operating system. Smart drives will internally relocate weak sectors before they become unreadable by remapping them to internal spare areas which will not be reported to the outside. Cheap drives typically have smaller reserved areas, whereas server drives have lots of them. The BIOS/operating system can query a drive's view on its fitnet via S.M.A.R.T. etc. --Matthiaspaul (talk) 16:36, 29 February 2012 (UTC)
thread_title:  Is LBA affected by remapped sectors? 

message: I have merged redundant sections from CHS conversion and Cylinder-head-sector; the former includes an assembly code example which is obviously too simple to work right, so I placed it here for review. --Dmitry (talk •contibs ) 22:29, 28 October 2010 (UTC)
thread_title:  Merge/assembly code 

message: You are correct that the code is wrong. Two problems exist in the current code. First, the cylinders and heads need to be swapped. Second, the cylinder is actually 10 bits big when working with the BIOS interrupts while the sector is only 6 bits big. It would be nice for someone to modify this code as this code has propagated through out the internet. (Tested using a custom made boot sector in Bochs emulating a 1.44MB floppy.)
--Jorgy343 (talk) 03:04, 26 December 2009 (UTC)
thread_title:  Incorrect LBA -> CHS Information 

message: What is the purpose of this paragraph? Modern SATA/SAS hard disks use LBA to adress its blocks, so a hardware RAID and/or external SAN drive (which most likely uses Linux inside) should feature a software layer which will make LBA translations between physical disks to present a disk array as a uniform logical drive to the OS. The same goes for SCSI or ATA/SATA device adressing - the software will virtualize LUNs of individual disks and present a unified LUN for the entire storage device.  Does it really deserve any specific mention in regard to LBA? --Dmitry (talk •contibs ) 12:08, 29 October 2010 (UTC)
thread_title:  LBA and LUN virtualization 

message: So I go to use Wikipedia and find that I got this message from Jeh (talk):
Please refrain from making test edits in Wikipedia pages, such as those you made to Logical block addressing‎, even if you intend to fix them later. 
Such edits appear to be vandalism and have been reverted. If you would like to experiment again, please use the sandbox. 
Thank you. Jeh (talk) 19:10, 10 February 2011 (UTC)
thread_title:  Jeh Needs to learn how to read 

message: In the 2nd para of Overview, it's not clear (to me, at least) whether "drive controller" refers to the PC's IDE or SATA controller, or the control board on the drive itself, though in either case it must be a LBA address which passes down the PATA or SATA cable.  —Preceding unsigned comment added by Pleriche (talk • contribs) 12:21, 9 May 2011 (UTC)
thread_title: Ambiguity in "device controller" - overview

message: That section does not seem to be entirely correct: NTLOADER-32 doesn't inherently prevent you from booting off a GUID partition table.
XP, 2003 32 bit versions can boot from SCSI drives: SCSI drives are typically not MBR CHS systems, and the logical disks may be identified by GUID in BOOT.INI if "drive/partition" information doesn't exist.  — Preceding unsigned comment added by 203.206.162.148 (talk) 04:40, 26 May 2011 (UTC)
thread_title:  os dependencies, guid partition table 

message: This is currently the first Google hit for LBA, which can at least mean linear bounded automaton, probably among other meanings.
Lucaswiman (talk) 17:01, 26 June 2012 (UTC)
thread_title:  Needs a disambiguation page