Talk:Wear leveling

message: hi, information about wear leveling is sparse on the internet. Companies keep their algorithms as a secret.
The white paper from sandisk is no exception. Sandisk removed the paper from all official pages so
it's very hard to find (Try to search for it!). So I'd like to find a nice place to upload this paper to.
Any suggestions where to archive it?
:Did you check whether the file is archived by The Wayback Machine? Brolin Empey 20:45, 12 May 2006 (UTC)
replies: text: Above link is currently 'DEAD', "The page cannot be found" --220 of  Borg 19:37, 5 December 2011 (UTC)
replies: text: But a Google search for "Sandisk Wear leveling" got it here at http://www.d.umn.edu/~cprince/courses/osresources/news/WearLevel.pdf  "W H I T E   P A  P E R :       S A N D I S K   F L A S H   M E M O R Y   C A R D S - W E A R   L E V E L  I N G,  October 2003", as the first result. • Query: Is this linkable or a copy-vio?- 220 of  Borg 19:48, 5 December 2011 (UTC)
replies: text:  Answer (a year later): A link to copyrighted external data is no problem. But data should never be copied to WP, whether copyrighted or not, because WP is actually written by its editors, based on reliable sources. David Spector (talk) 21:46, 16 May 2013 (UTC)
thread_title:  Attach PDF file 

message: The comment about the sandisk wear leveling not working for the FAT is incorrect, the comment assumes that the first 4Mb of the host visible sectors are in the same zone. This will definitely NOT be the case, any normal filesystem will tend to cluster writes in small areas of the 'disk' for performance reasons (on hard disk drives). This means that it the 'erase block' is one sector the best layout for a 4Mb zone on a 1Gb device is for every 256th sector to be in a given zone. The size of the 'erase block' does confuse this though.
I'm not sure if the paragraph should be rewritten or just deleted. 86.16.135.53 10:06, 27 May 2006 (UTC)
thread_title:  Comment about FAT File system 

message: I disagree with "Some storage interfaces like DiskOnChip (which allows flash memory devices to emulate regular ATA disks) do not in themselves perform wear levelling." 
From the Emphase website describing a Flash disk module 44-pin: "Wear-leveling algorithm to increase module lifetime"
http://www.emphase.com/fdm4400
informedbanker
:I'd like a reference for this too. Most commercially available parallel ATA flash modules use the CompactFlash form factor of ATA, and as I understand the article, most commercially available CF cards perform wear levelling. I've requested a citation, and I plan to come back in a week and remove the claim if nobody cites it. --Damian Yerrick (talk | stalk) 12:59, 17 July 2007 (UTC)
replies: text: By now, 2.5" and 3.5" flash solid-state drives based on SATA or parallel ATA have become common, but the controllers on these are even less size-constrained than CF and thus more likely to wear-level their physical medium. --Damian Yerrick (talk | stalk) 16:53, 11 September 2009 (UTC)
thread_title:  Comment about DiskonModule wear leveling 

message: Does anyone have a reference for the article's claim that the SD standard uses wear leveling?  —Preceding unsigned comment added by 216.75.169.65 (talk) 23:19, 17 August 2008 (UTC)
replies: text: I don't see any claim in the article that the Secure Digital spec requires wear levelling, just that cards do use it. SD is just a protocol and three form factors; I don't think it specifies any methods of wear levelling. But any card that doesn't use it will likely get trashed in the market. --Damian Yerrick (talk | stalk) 00:59, 18 August 2008 (UTC)
replies: text: That doesn't seem to have happened.  SmartMedia didn't have wear levelling, though that card is now obsolete. The xD card is in reality just a miniaturised SmartMadia card.  It is electrically identical right down to the lack of wear levelling controller because the host device has to communicate with flash chip directly.  Some SmartMedia devices can use the smaller xD cards via an adaptor (geometry being the only limitation as the xD card is thicker). It is still firmly in the market place though only a minority of devices use it. 20.133.0.13 (talk) 12:35, 10 September 2009 (UTC)
replies: text: But in fact, xD has been trashed by SD. See the lead of xD-Picture Card: even Olympus and Fuji are moving to SDHC. Feel free to close your eyes and laugh out loud. --Damian Yerrick (talk | stalk) 17:03, 11 September 2009 (UTC)
thread_title:  SD and compact flash wear leveling 

message: This article omits specific mention of significant differences in algorithms used to perform wear levelling, or, to be specific, the difference between dynamic wear levelling and Static Wear Levelling.Wear Leveling Application Note by Spansion 68.177.173.34 (talk) 20:16, 29 January 2010 (UTC)
replies: text: This has apparently been fixed. David Spector (talk) 21:49, 16 May 2013 (UTC)
thread_title: Different Wear Levelling Algorithms Not Discussed

message: The content below was pulled from the original Static wear leveling article before it was merged with this one. Original comments on this talk page identified this article as being too technical and not truly descriptive of Static wear leveling. If anyone finds data here that they believe is useful in the new combined main article please add it and note what is covered by marking out the text here. § Music Sorter § (talk) 00:02, 14 August 2010 (UTC)
thread_title:  Unused content from original Static Wear Leveling article 

message: I am not yet able to find an answer to this question regarding wear leveling:
For the NAND flash memory (flash drive) to be transparent to the OS, it needs to have a controller on the chip and store a wear level mapping (LBA to PBA) on the device. The question is, where is such mapping table stored?
If the mapping table is also stored on the flash memory, it needs to be updated every time a write command is received. Therefore, the blocks that store the mapping table will wear out first, while other data blocks are not worn out yet.  — Preceding unsigned comment added by 131.107.0.81 (talk) 23:16, 30 December 2011 (UTC)
replies: text: This is not a forum. The answer to your question is dependant upon which exact device you are using, they all different. HumphreyW (talk) 00:02, 31 December 2011 (UTC)
thread_title:  Wear leveling mapping blocks wear out first 

message: The article could detail what is the size of one remapped data chunk. I assume it can't be very small as then all the remapping data would consume enormous amount of space. 84.248.91.142 (talk) 16:28, 28 September 2012 (UTC)
replies: text: Each system is different. There is no predefined size that everything uses. HumphreyW (talk) 01:19, 29 September 2012 (UTC)
thread_title:  Size of one remapped block 

message: You have wrote that "Blocks or sectors on the media can be tracked in a least recently used queue of some sort."
 I disagree with least recently used queue of some sort and I think it should be least frequently used queue. Also LFU can be categorized as one of LRU algorithms but I think other LRU algorithms (e.g. Aging) are not suitable for this purpose, because unlike paging applications that try to replace the least recently used page, here exactly the least frequently used block/sector should be rewritten, since number of writing operations accumulate over time.
e.g. If block A was written 1000times 1 year ago and block B was written exactly 1 time 1ms ago, LRU will choose block A for rewriting which is not optimum but LFU will choose block B which is better choice.
 My claim could be false only if you bring a practical example of a kind of LRU which is used as proper algorithm in real life.  --digitsm (talk) 01:56, 26 November 2013 (UTC)
replies: text:  You're right, thank you for pointing that out.  Already went ahead and edited the article, please check it out. — Dsimic (talk) 02:42, 26 November 2013 (UTC)
thread_title:  "Least Frequently Used" Should be used instead of "Least Recently Used"