LinuxQuestions.org
Register a domain and help support LQ
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware
User Name
Password
Linux - Hardware This forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

Notices

Reply
 
LinkBack Search this Thread
Old 05-30-2011, 01:47 AM   #1
sulekha
Member
 
Registered: Dec 2004
Location: India
Distribution: ubuntu 10.04 , centos 5.5 , Debian lenny, Freenas
Posts: 324

Rep: Reputation: 36
Question NAND based flash memory


SSD's are NAND based flash memory isn't it ?

which means that they have limited no: of writes ?

so my questions are as follows

1) after completing this limited no: of writes , will an SSD drive become un-usable ?

2) according to the article given here:-

http://www.tomshardware.com/forum/20...-samsung-flash

Flash has a limited no. of writes, usually a maximum of 100,000 operations in the same location.

Does that mean that at the time being, HDD's are a better proposition when compared to SSD's ?
 
Old 05-30-2011, 07:04 AM   #2
salasi
Senior Member
 
Registered: Jul 2007
Location: Directly above centre of the earth, UK
Distribution: SuSE, plus some hopping
Posts: 3,860

Rep: Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768
Quote:
Originally Posted by sulekha View Post

1) after completing this limited no: of writes , will an SSD drive become un-usable ?
No. Look up wear levelling.


Quote:
Originally Posted by sulekha View Post
Does that mean that at the time being, HDD's are a better proposition when compared to SSD's ?
No. What determines which is a better proposition is largely economics. So to determine which is better, you have to look at the economics of the application. If you could say which was a better proposition without considering the application, there would probably only be one on the market.
 
Old 06-01-2011, 12:26 AM   #3
sulekha
Member
 
Registered: Dec 2004
Location: India
Distribution: ubuntu 10.04 , centos 5.5 , Debian lenny, Freenas
Posts: 324

Original Poster
Rep: Reputation: 36
Lightbulb

Intel's MLC SSDs has got a life span of 100GB per day x 5 year

after some researching on the net this is what i have concluded


Pros of SSD:-

1) less power consuming
2) no spin-up time
3) fast random access to data


Cons of SSD:-

1) High cost per G.B
2) lower drive capacity
3) relatively low write speed
4) wear leveling to ensure a single block of flash memory is not used extensively
5) wear leveling can cause problems with data encryption techniques
 
Old 06-01-2011, 04:54 AM   #4
salasi
Senior Member
 
Registered: Jul 2007
Location: Directly above centre of the earth, UK
Distribution: SuSE, plus some hopping
Posts: 3,860

Rep: Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768Reputation: 768
Well, that's a surpise:

Quote:
Originally Posted by sulekha View Post
Intel's MLC SSDs has got a life span of 100GB per day x 5 year

after some researching on the net this is what i have concluded


Pros of SSD:-

1) less power consuming
2) no spin-up time
3) fast random access to data


Cons of SSD:-

1) High cost per G.B
2) lower drive capacity
3) relatively low write speed
4) wear leveling to ensure a single block of flash memory is not used extensively
5) wear leveling can cause problems with data encryption techniques
After reading you initial post, I had no idea that this would have been the type of information that you were trying to get. There are a couple of points that are questionable, but, in general, you have the right idea. The cost per gigabyte of capacity is higher, but they have some performance advantages.

I don't directly see wear levelling as a disadvantage; yes, you pay for someone to incorporate wear levelling into their chips, but once it is there, it is there, and you don't, as a user, have to do anything else to make it happen, and it improves the longevity of the device.

And, relatively low write speed? Relative to what? If it is only relative to the read speed of an SSD, then it is not really a disadvantage so much as a lack of an advantage.

Just to quote a rather extreme 'corner case' at you; imagine a case in which there is a database server, which primarily does reads rather than writes on a small-ish data set; it could be the case that in order to get adequate performance with conventional hard drives you would have to add an extra server to get extra spindles...even if that wasn't a problem from cooling/power points of view, it would be clear that adding this extra server would be more expensive than substituting a single small SSD for a hard drive in the critical part of the database.

(There would also be the possibility of using higher performance hard drives, but you'll be surprised how much that these have higher costs per Gb than standard, consumer, drives.)

So, in this, admittedly extreme, case you can argue that the advantage of SSDs is that they are cheaper when looked at from a systems point of view. While this is not the normal case (if it was the normal case, more people would be using SSDs for their home computers), I am pointing this out to ensure that you aware of the dangers of over-generalisation.
 
  


Reply

Tags
hdd, ssd


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Unable to mount root fs: s3c2410 based board, Nand flash swapnilborg Linux - Embedded & Single-board computer 4 10-07-2011 11:43 AM
Nand flash boot Roger03 Programming 1 04-03-2010 05:19 AM
A question about u-boot in Nand flash dongbo Linux - Hardware 0 10-15-2009 04:25 AM
R/W from nand flash linux_newbie79 Linux - Newbie 3 08-19-2009 08:35 AM
nand flash: need help jier Programming 0 05-03-2006 11:05 PM


All times are GMT -5. The time now is 05:39 AM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration