To mmc or not to MMC

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To mmc or not to MMC

Unread postby aikiguy » Sat Jul 26, 2014 6:38 am

I am trying to get an order in for a U3 to play with doing some Small boat applications, (chartplotter, media machine, light office, etc).

My question is should I get a preloaded emmc card to go with it?
Is there a big speed difference?
Reliability, I have heard that the emmc cards are not as robust as even a sd card.
I have a ton of micro sd cards already, does the emmc card offer benifits over an sd card?

Thanks,
Guy
:-)
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Re: To mmc or not to MMC

Unread postby meveric » Sat Jul 26, 2014 8:15 am

eMMC is faster.. eMMC is around 50MB/sec SD is limited to about 15MB/sec (seems to be an issue with the BUS)
SD break down every now and then as well, especially with a lot of I/O operations on the card (for example due to compiling). But they are cheap and easy to get.

I guess it really depends on your needs.. Do you need high speed on starting programs (once they are open they are in memory so no loading is needed), do you need high speed on booting? Then go get an eMMC.
Will eMMC break down as well?
Yes they definately will. And if you do alot of I/O operations, they probably break down faster as well. (might not be as fast as a SD though)

eMMC are rather expensive and you have to order them from hardkernel, so together with the shipping, it 16GB will cost you about $ 70~75 with shipping and fees.

SD Card 16GB you get for around $ 10. So it's up to you what you need and what you are willing to pay :)
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Re: To mmc or not to MMC

Unread postby darth_llamah » Tue Aug 19, 2014 4:00 am

meveric wrote:eMMC is around 50MB/sec SD is limited to about 15MB/sec (seems to be an issue with the BUS)

I guess this is also due to bus width- SD is max 4-bit while eMMC can work using 8-bit wide bus

meveric wrote:Will eMMC break down as well?
Yes they definately will. And if you do alot of I/O operations, they probably break down faster as well. (might not be as fast as a SD though)

I was about to ask about this :)
How much better is lifespan of eMMC compared to SD? I've already killed 2 SD cards dd-ing images (first sectors are apparently dead, cards can still be used as storage media)
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Re: To mmc or not to MMC

Unread postby sert00 » Tue Aug 19, 2014 4:51 am

me too i broke some microSD by DDing...i speak about that some days ago here on community,had and have lot less problems with UHS-i cards.
I noticed the majority of dead cards i had,was non UHS-I.
Anyways to OP,if he have yet to do the order,i reccomend buy an EMMC...if inside the order of the board,taxes and fees will be divided for all the items and he has the emmc in case later on will consider the microSD slow.
This way also,if want to try android it's better suited on an EMMC,and leave linux on one of the already owned microSD he spoke off (better if UHS-I)
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Re: To mmc or not to MMC

Unread postby grsingla » Wed Apr 15, 2015 1:18 am

Hi,

We are using Odroid XU+E and Odroid XU3.
2-3 boards did not power up when we connected emmc cards.
These boards were working fine initially, even without making any changes to the emmc cards, the boards suddenly stopped working.
Is it a problem of robustness or something else?
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Re: To mmc or not to MMC

Unread postby venkatbo » Wed Apr 15, 2015 4:11 am

I wonder if it possible to have all writable dirs of an installation use an external usb crad through a minimalist adapter/reader like this:
41nEXew42DL._SY355_.jpg
41nEXew42DL._SY355_.jpg (9.2 KiB) Viewed 1428 times
available at: http://www.amazon.com/elago-Mobile-micr ... B002HGFKR8. The main sdcard can have a read-only FS.

We can then get rid of the failing sdcards easily.
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Re: To mmc or not to MMC

Unread postby odroid » Wed Apr 15, 2015 10:20 am

grsingla wrote:Hi,

We are using Odroid XU+E and Odroid XU3.
2-3 boards did not power up when we connected emmc cards.
These boards were working fine initially, even without making any changes to the emmc cards, the boards suddenly stopped working.
Is it a problem of robustness or something else?


The eMMC cards for the XU can't be used on XU3 if you don't install a proper boot loader.
Also check the DIP switch settings too.
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