Take the 2-minute tour ×
Raspberry Pi Stack Exchange is a question and answer site for users and developers of hardware and software for Raspberry Pi. It's 100% free, no registration required.

I'm planning to use my pie 24/7, but SD cards are not made for this. Because of that I want to reduce the read and write jobs on the card so it will last longer. There are several options to do this;

  • I could use an external hard drive to run real time programs on;
  • I could use an USB stick to run real time programs on.

I prefer an USB stick because it doesn't make noise, but it also uses flash memory. So is it wise to buy an USB stick for real time jobs? Because then I could store everything on the USB stick, except the OS of course.

share|improve this question
    
I have a 2 ampere power supply, so in my case you don't need to worry about the power supply. I have an model B 256 MB version. –  Laurence Nov 15 '12 at 12:59
2  
You should also look at How can I extend the life of my SD card?. Large SD cards are so cheap now that overprovisioning can easily give you the longevity you need. –  Mark Booth Nov 15 '12 at 14:15
    
@MarkBooth You could turn that into an answer :) –  XTL Nov 16 '12 at 8:39
    
@XTL - It's not really an answer to the question asked, it's an answer to a slightly different question that I think is still relevant, hence leaving it as a comment but linking to my answer to the other question. –  Mark Booth Nov 16 '12 at 13:58
add comment

1 Answer

up vote 1 down vote accepted

I did some calculations:

An USB with SLC NAND Flash can do maximum 100.000 write cycles. On an USB with 8GB with 10 MB/s write speed will that be:

(My math skills or not very good, I know for sure you can do this on an easier way)

((8192 / 10 )) * 100.000) / (365.242 * 3600 * 24) = 2.595945012206012 years.

So, when you write on your USB with 10 MB/s for 2,6 years it will be broken. Its true that it will be broken earlier. but when you have a good controller it will last very long. So yes, an USB with SLC NAND flash is a good option.

You also have SD cards on SLC NAND flash, but I don't know the technical details about the controller in the Raspberry pi, besides that. In my country an USB stick is cheaper then a SD card. So I bought a small SD card and an USB stick.

There is one downside, an USB stick needs power. USB can max consume 0.5 ampere. Model A of the PI has a limited USB power output, and not every power supply’s can handle that much amperes. So you need to check this before you buy an USB stuck for your PI.

Source: “SLC NAND flash is typically rated at about 100k cycles (Samsung OneNAND KFW4G16Q2M) ” on the page: http://en.wikipedia.org/wiki/Flash_memory

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.