Talk:COMP 3000 Essay 1 2010 Question 10

Hey all,

I think we should write down our emails here so we can further discuss stuff without having to login here. (***Note that discussions over email can't be counted towards your participation grade!***--Anil)

Geoff Smith (gsmith0413@gmail.com) - gsmith6

I used Google Scholar and came to this page http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=812717&tag=1# Which briefly touches on the issues of Flash memory. Specifically, inability to update in place, and limited write/erase cycles.

Inability to update in place could refer to the way the flash disk is programmed, instead of bit-by-bit, it is programmed block-by-block. A block would have to be erased and completely reprogrammed in order to flip one bit after it's been set. http://en.wikipedia.org/wiki/Flash_memory#Block_erasure

Limited write/erase: Flash memory typically has a short lifespan if it's being used a lot. Writing and erasing the memory (Changing, updating, etc) Will wear it out. Flash memory has a finite amount of writes, (varying on manufacturer, models, etc), and once they've been used up, you'll get bad sectors, corrupt data, and generally be SOL. http://en.wikipedia.org/wiki/Flash_memory#Memory_wear

Filesystems would have to be changed to play nicely with these constraints, where it must use blocks efficiently and nicely, and minimize writing/erasing as much as possible.

I found a paper that talks about the performance, capabilities and limitations of NAND flash storage.

Abstract: "This presentation provides an in-depth examination of the fundamental theoretical performance, capabilities, and limitations of NAND Flash-based Solid State Storage (SSS). The tutorial will explore the raw performance capabilities of NAND Flash, and limitations to performance imposed by mitigation of reliability issues, interfaces, protocols, and technology types. Best practices for system integration of SSS will be discussed. Performance achievements will be reviewed for various products and applications. "

Link: http://www.flashmemorysummit.com/English/Collaterals/Proceedings/2009/20090812_T1B_Smith.pdf

There's no Starting place like Wikipedia, even if you shouldn't source it.

http://en.wikipedia.org/wiki/Flash_Memory

http://en.wikipedia.org/wiki/LogFS

http://en.wikipedia.org/wiki/Hard_disk

http://en.wikipedia.org/wiki/Wear_leveling

http://en.wikipedia.org/wiki/Hot_spot_%28computer_science%29

http://en.wikipedia.org/wiki/Solid-state_drive

Hey Guys,

We really don't have much time to get this done. Lets meet tomorrow after class and get our bearings to do this properly.

Fedor

A few of us have Networking immediately after class. I know personally I won't be able to make anything set on Tuesday. Additionally, he spoke briefly about hotspots on the disk for our question last week, where places on the disk would be written to far more often than others. As well, for bibliographical citing, http://bibme.org is a wonderful resource for the popular formats (I.e. MLA). If it should come down to that. ~Andrew

links

Start Posting some stuff to source from:

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1199079&tag=1 --"Introduction to flash memory"

http://portal.acm.org/citation.cfm?id=1244248 --"Wear Leveling" (it's about a proposed way of doing it, but explains a whole bunch of other things to do that)

http://portal.acm.org/citation.cfm?id=1731355 --"Online maintenance of very large random samples on flash storage" (ie dealing with the constraints of Flash Storage in a system that might actually be written to 100000 times)