microSD Card classes - Nook Color General

Hi guys. I was wondering if there are any issues making bootable SD cards for honeycomb or froyo and etc.
I am thinking of buying an micro sd card for the nook color.
which one of you guys would recommend?
16GB class10? 8GB class10?
I have seen all mostly using 8gb or 4gb at most. is there any issue using 16gb class10? please advice. thanks!

should be fine.

waiteck said:
Hi guys. I was wondering if there are any issues making bootable SD cards for honeycomb or froyo and etc.
I am thinking of buying an micro sd card for the nook color.
which one of you guys would recommend?
16GB class10? 8GB class10?
I have seen all mostly using 8gb or 4gb at most. is there any issue using 16gb class10? please advice. thanks!
Click to expand...
Click to collapse
If they are same class then you should get about the same speed off either and all your looking at is size... if you want 8gb of space get the 8gb if you want 16gb of space get that one instead.....
I would not recommend using anything lower than a Class 6 card however.

I've run HC on a 8gb class 4 card for a while. No real problems. Maybe lags a little time to time, but that may also just be the rom.

i see... initially i thought there were issues with class10 16gb cards.
thanks all for the input!

I purchased two 8GB Class 10 cards. I use one for storage and the other for Honeycomb and it runs great.

Can the Nook actually even use the speed of a class 10? I know many phones can only fully use 4 or 6, with the only benefit of 10 being faster transfer while connected directly to PC. Class 2 is just slow on everything, of course .

waiteck said:
i see... initially i thought there were issues with class10 16gb cards.
thanks all for the input!
Click to expand...
Click to collapse
I tried class 10 and class 4 16gb cards because I really wanted the space. I had all sorts of problems running on the class 10 once v04 honeycomb came out and the class 4 would run froyo and HC but it was so slow it couldn't be used. Some people seem to be using them but when I relaced it with a 8gb class 10 Patriot card, it runs great.
As to whether the nook can use a class 10, I don't know. I certainly know it MUCH faster with a class 10 than a class 4. I also bought a class 6 AData card but I have not tried it as a speed comparison. I was just tired of running back to the store to return them and test another so I bought two and started with the fastest one.
16gb might work with future versions but for now, I am sticking with 8gb cards.
I recommend the Patriot 8gb Class 10. The model I bought was the LX Signature Series: PSF8GMCSDHC10

therealguppy said:
If they are same class then you should get about the same speed off either and all your looking at is size... if you want 8gb of space get the 8gb if you want 16gb of space get that one instead.....
I would not recommend using anything lower than a Class 6 card however.
Click to expand...
Click to collapse
Not necessarily. Class only implies a guaranteed minimum WRITE throughput, e.g. class 4 = 4MB/s, class 6 = 6MB/s, etc. that a particular class of card is capable of supporting. There is no guarantee that the tablet, camera, etc. is actually capable of achieving/sustaining that throughput rate though.
Read throughput can be anything, but are usually close to write speed, and another factor not as important most of the time with tablets is the latency of r/w accesses.
In the pre-SDHC days Japanese made(Toshiba - only Japanese maker) uSDs were the best in terms of speed and latency, followed by most Taiwan(various) made cards. Chinese(various) made cards were the worst by FAR. Also the pre-SDHC uSDs had varying r/w throughput and latency depending upon how "full" they were with the same general rule as above applying as to where manufactured. Presumably this is not the case with SDHC as the class implies that regardless of how full a card is that it WILL maintain that minimum write throughput.
8 v. 16: From the pricing that I've seen 2 8GB cards are cheaper than a single 16GB -> 8GB a better deal IMO. e.g. class 6 8GB are <$15 while 16GB class 10 are >$35 at least on newegg...
Another factor to consider is that you likely don't need a class 10 card unless you happen to have a very high performance/high resolution digital video recorder... i.e. class 2 is likely even good enough for most tablet video and other applications, but since class 6 cards can be had at reasonable prices(online, b&m are profiteeringly insane in their markups) those would probably be the best choice.
[EDIT]
I'll let you know about class 4 4GB uSDs as a local b&M unbelievably has an approximately reasonable price on PNY(probably Taiwan) class 4 4GB uSDs, $10 which is cheap enough to pitch them if they're junk or use them for applications that don't require high throughput.
(On a side note most class 4 and class 6 uSDs work great with Nintendo DSes, which I'd suspect are MUCH more sensitive to throughput and access latencies... or so I've read...)
[/EDIT]

I see Stevr had posted which Patriot he had success with in Post #8 of this thread, and in the HC Preview v4 thread there have been a few negative posts about certain cards not livinig up to their class ratings... so I have to ask...
Is there a single thread recommending or comparing the various MicroSD cards, how they've worked for Froyo or HC booting/running off them? (i.e. a central posting of "this one works great..." or "this one is too slow"?)
EDIT: I found this talking about cards for Froyo from SD -> http://forum.xda-developers.com/showthread.php?t=946896 which has some makers, size and class.. no specific model numbers.

KidJoe said:
I see Stevr had posted which Patriot he had success with in Post #8 of this thread, and in the HC Preview v4 thread there have been a few negative posts about certain cards not livinig up to their class ratings... so I have to ask...
Is there a single thread recommending or comparing the various MicroSD cards, how they've worked for Froyo or HC booting/running off them? (i.e. a central posting of "this one works great..." or "this one is too slow"?)
EDIT: I found this talking about cards for Froyo from SD -> http://forum.xda-developers.com/showthread.php?t=946896 which has some makers, size and class.. no specific model numbers.
Click to expand...
Click to collapse
seems like alot of 16gb class 10 are having issues with running froyo off memory cards.
might get a 8gb class 10 instead. and a spare 16gb class 10.

Related

[Q] About SD Card

Hello
I got my Legend about 2 months ago, and I have a big problem with storage space...
What is the biggest sized SD card the Legend can use?
What is the type of SD card (micro, mini, etc...)
What is SD card class?
Thank you very much
microSD compliant with SD2.0 Standard (aka microSDHC)
The biggest size available currently is 32GB.
I don't know if even more is possible with microSDHC or if bigger cards will only be possible with SD3.0 (aka SDXC) but that question is not relevant as you can't buy any greater then 32GB yet.
The Class of the SDCard is a measurement for guaranteed minimum speed in random read/write.
The Class does not provide any information about real-world speed or max speed.
For your mobile phone the class is a pretty useless criterion as you don't need any guaranteed minimum speeds but good overall speeds ESPECIALLY sequential.
The guaranteed minimum speed is important for HD Video Cameras for example where you write data all the time at a given speed (resolution).
thanks.
but I DO need class with high speed because I want to use Data2Ext...
Don't pick uSD card based on class !! class tels you MB/s for sequential write only... you need a card that is overall fast, I had 16GB class 10 Kingston and data2ext was just horrible!
Now I'm with class 4 Sandisk mobile ultra and it is in fact faster in every test I ran...
So read reviews before you buy
ye but that is exactly why im asking...
well then, I recommend sandisk mobile ultra as I have it and it is OK, there are probably faster cards...just see the small files read / write speeds in reviews those are of greatest importance
i purchased a kingston 8GB class 4 which crapped out. android kept reported sdcard unexpectedly removed. tried all sorts (formatting in windows, android, quick, long, etc).
RMA replacement did exactly the same, so i'm guessing kingston class 4's are best avoided.
If I recall correctly I have a 16GB microSDHC Class 4 card. After applying data2ext with this card, my Quadrant scores hit around 1500, which is crazy.
This is where I found my card: http://www.amazon.co.uk/SanDisk-16G...P06K/ref=sr_1_1?ie=UTF8&qid=1298984123&sr=8-1
I personally recommend this card.
witch is better class 4 or class 6?
r69001 said:
Hello
I got my Legend about 2 months ago, and I have a big problem with storage space...
What is the biggest sized SD card the Legend can use?
What is the type of SD card (micro, mini, etc...)
What is SD card class?
Thank you very much
Click to expand...
Click to collapse
Did you by any chance go to HTC's website to read about the phone? It has the full specs listed..
Sent from my Legend using XDA App
dangal said:
witch is better class 4 or class 6?
Click to expand...
Click to collapse
class 6 is better , but class 10 is even better
I've got a Sandisk Ultra Mobile 16gb SDHC which works fine in the Legend. Make sure you format it with the phone to stop it being dismounted, well known issue and the fix

Which microSD card is the MOST STABLE and FASTEST for using HoneyComb in SD card?

So I finally got HoneyComb working on my Nook Color (NC), residing in the microSD card using a Kingston 8GB Class 4. However, this card seems to be one of the slowest and using the HC in NC is almost unusable.
Example:
- Screen rotation takes 3-5 seconds
- Opening new app, depending on which app, can take 1-5 seconds
- Browsing certain website can make the screen unresponsive
- etc..etc..
I know that the HC version available in this website is probably still in "preview" or beta stage and some slowdown is expected, but I am not expecting it to be THIS bad. So I think the culprit is the microSD card itself.
However, I have tried many different MicroSD card and none works. I.e. it gives the "decrypt storage" error when booting up the NC. The cards I have tried are:
- Patriot 16GB Class 10
- A-Data 16GB Class 10
- Kingston 8GB Class 6
The ONLY one that works so far is Sandisk. Unfortunately, from SanDisk website, I do NOT SEE ANY card higher than Class 4.
Thus, can you recommend which is the MOST STABLE and FASTEST card? I.e. the ones that did NOT give slowdown per the examples I have given above.
i'm using sandisk 4 GB class 4 HC
nookie froyo, runs fantastic.
Class 10 cards apparently dont do too well. lots of people have had issues with those. class 6 should be OK, class 2 and 4 workk very nice.
Do you have recommendation for a good Class 6 MicroSD card? SanDisk don't sell anything higher than Class 4. I tried Kingston Class 6 and my Nook Color just spit on it...
lanwarrior said:
Do you have recommendation for a good Class 6 MicroSD card? SanDisk don't sell anything higher than Class 4. I tried Kingston Class 6 and my Nook Color just spit on it...
Click to expand...
Click to collapse
I am currently running trancend 8gb class 6. Havent had any issues with froyo, HC or Cm7 booting or running.
I'm using a A-Data Class 6 16Gb card with no trouble. I do have 2 Kingston Class 4 32Gb cards and they have the issue with the decrypt garbage when you try to boot up HC from the sdcard. I've also got a Class 10 32Gb Wintec card which I have not had time to test out yet as I just got it the other day.
After a failed Kingston 16gb class 10, I got a SanDisk 8gb Class 4 and it's speedy enough. I notice very minimal slow down on some menus but I don't know if that's just the OS itself (being a preview after all)
danootz said:
After a failed Kingston 16gb class 10, I got a SanDisk 8gb Class 4 and it's speedy enough. I notice very minimal slow down on some menus but I don't know if that's just the OS itself (being a preview after all)
Click to expand...
Click to collapse
That's the exact same card I have, and you did NOT experiences any of the slowness I posted in my 1st thread?
How drastic is the difference between Class 2 and Class 4?
I know that it says that it processes twice as fast, but is it noticeable? Can somebody give an example of when you can actually tell the difference? Playing music, watching movies, booting from microsd?
I have a Sansdisk class 2 8gb card that performs just as well as my class 10 Patriot 8gb (which has booted both HC and currently used as storage for my eMMC CM7 install.)
Sansdisk severely underrates their SD's and many other manufacturers overrate theirs. It is not a perfect rating system.
I would recommend going w/ sansdisk in whatever size you can afford. Class 2/4 will be plenty fast.
Before I switched back to Froyo I was running off the SanDisk 8Gb card from BestBuy - $20 - which I found very responsive. I think it is Class 4, but I could see any label on the card itself or the package.
The SD card speed was not the reason I switched back, it was the lack of other features in HC preview. I can't wait for an AOSP release
8GB Cards
I currently have 2 8GB microsds that I switch between:
-Transcend 8GB Class 6 running Honeycomb from Amazon. Tested it with h2wtest and got 16MB/s write and 14MB/s read. (Not sure if that is a typo on the tool or not and it's supposed to be bits instead of bytes, but that's what it says).
-Sandisk 8GB Class 2 running Nookie Froyo. Tested at 14MB/s write and 18MB/s read.
Both cards run their respective ROMs well, so it seems to jibe with what chisleu said about Sandisk underrating their cards. I could also be limited by the USB adapter I was using, but I had another adapter that was limiting it to 4MB/s both ways.

Best uSD card to run CM7

I just put one of the CM nightly builds (build38) on a uSD card (sandisk 16gb class 2) and there is a major lag to even enjoy the device. I have been reading about that sometimes class numbers on the cards don't mean too much.
Which card would you recommend to run CM from (Brand/class/where to buy) from your experience?
any class 6 card should be plenty enough (as long as it has enough room for the ROM and stuff) even class 4 should work much better (but still some lag i beleive, idk ive never tried it)
newegg is a pretty good place to shop for them. Heres one such card - newegg.com/Product/Product.aspx?Item=N82E16820211341&cm_re=8gb_micro_sd_card-_-20-211-341-_-Product
There is a long thread about this on here and the class 6 Transcend 8GB card got the most mentions for good perfomance. The probability for issues to arise increases when using cards over 8GB.
I have a class 2 Sandisk 8GB and class 6 Transcend 8GB card. They both work well.
I have been buying the Wintec cards from newegg for a couple months and run them in both my captivate and my nook they work awesome. Class 10 and fast. http://www.newegg.com/Product/Product.aspx?Item=N82E16820161411
Patriot Signature 8 GB Class 10 MicroSDHC
Did anybody have any experience with this card?
http://www.amazon.com/Patriot-Signa...I8MS/ref=sr_1_2?ie=UTF8&qid=1302629334&sr=8-2
rahlquist said:
I have been buying the Wintec cards from newegg for a couple months and run them in both my captivate and my nook they work awesome. Class 10 and fast. http://www.newegg.com/Product/Product.aspx?Item=N82E16820161411
Click to expand...
Click to collapse
Are you running a rom (e.g CM7) off the card? Did you ever run a speed test?
onurd said:
Are you running a rom (e.g CM7) off the card? Did you ever run a speed test?
Click to expand...
Click to collapse
Not at this time. What speed test would you like if I loaded one up on the card and booted from it?
onurd said:
Did anybody have any experience with this card?
http://www.amazon.com/Patriot-Signa...I8MS/ref=sr_1_2?ie=UTF8&qid=1302629334&sr=8-2
Click to expand...
Click to collapse
I used that card for HC v4 and it was fine.
I've got 4 uSD card: one Dane-Elec 2G no class, one Kingston 2G no-class, one Transend 4GB class 6 and one PNY 8GB class 4. All run CM7 very well, maybe I didn't pay attention but didn't notice much different in performance. In benchmark, the write speed is about 5-7 MB/s.
The higher capactity 16GB card seems to have more problems, other than that every card will do.
You should check into the random read/write performance of small files on these cards. sometimes the class 6 or 10 aren't all they are cracked up to be. Fast transfers of large file yes, but general performance can suck.
sandisk class 2 or 4 cards can have excellent perf. I have a class 10 that is outperformed by class 2/4 and 6 cards.
if you are having problems with crashing, etc. try a basic sandisk and see if perf. is better.
there is a thread about it but i can never find it.

Which SD Cards are the best ?

I couldn't find a real answer to this anywhere, but I plan on installing CM7 to an SD Card - and boot/run from the card.
Which class of SD card should I be shooting for - and why? Are there any certain brands that work well/don't work well? The same for sizes - is 16GB going to be faster than 32GB ?
Thanks. I'm shooting for a 16 GB internal which should be more than enough space.
Sandisk class 2 or 4
Sent from my LG Optimus V using Tapatalk
Search this forum and you will find that the Sandisk class 4 disks are great. The best part is they are available at most retail stores, if your impatient. I've been using a 16gb card for a while and it runs stable and smooth.
+1 vote for Sandisk
SanDisk class 4.
Sent from my NookColor using xda premium
SanDisk class 4, 16GB
see the other topics here about sd cards, there are some good known resellers on Amazon who have real SanDisk cards, not the fakes that you can finds for cheaper some places online.
Are there known issues with other brands or faster (eg; class 6 / 10) SD cards on the NC, or is it just when booting the likes of CM7 from them?
SamboNZ said:
Are there known issues with other brands or faster (eg; class 6 / 10) SD cards on the NC, or is it just when booting the likes of CM7 from them?
Click to expand...
Click to collapse
Some other cards do have known issues or possibly don't live up to their speed class rating. You might get lucky and get a decent one out of a bunch, but its very hit or miss. Other cards have also been known to die after using them for a bit.
If you're looking for something that is reliable and is consistent, then stick with SanDisk class 4.
SamboNZ said:
Are there known issues with other brands or faster (eg; class 6 / 10) SD cards on the NC, or is it just when booting the likes of CM7 from them?
Click to expand...
Click to collapse
I tried A-data 4GB and 8GB class 6, they both run great, tried a generic 16GB class 4, horrible slow. Haven't try any SanDisk yet.
sandisk 8gb class 4 seems to work ok for me
if i went anything larger than 8gb i would want above class 4 speeds i think
Read first post here:
http://forum.xda-developers.com/showthread.php?t=1005633
sandisk CL4, 8GB and 16GB seem to be the best bet. faster cards appear to be optimized for speed and large file transfers, but the CL4 and slower cards have better small file read/write speeds.
runnnig CM7 off the card, you want the better small file read/write speeds from the CL4 and slower cards.
~mike
Anyone tested any Sandisk Class 6 cards?
Amazon Basics class 10 sdcards work pretty good for me...but i have never run a rom from the actually sd card.
But for $28 (16gb) it actually is class 10-i have all my music and videos and they all perform well. I used to get force closes on my music player back when i had music on internal memory but now that its on external sd i have no force closes
In conclusion the 16gb class 10 amazon basics for $28 has improved my phone satisfaction
Sent from my SAMSUNG-SGH-I997 using XDA App
Found one result for a Sandisk Class 6:
http://forum.xda-developers.com/showpost.php?p=21268438&postcount=317
Seems to perform well!
This does not hold if you are running off the card. I have a 16GB class 6 Kingston and it runs terribly slow. My class 4 sandisk 16GB runs great.
Sent from my NookColor using Tapatalk
prettedda said:
This does not hold if you are running off the card. I have a 16GB class 6 Kingston and it runs terribly slow. My class 4 sandisk 16GB runs great.
Sent from my NookColor using Tapatalk
Click to expand...
Click to collapse
+1
Before I committed to emmc my lower class cards ran faster.
Sent from my GT-P7510 using one finger.
What monkeymike said.
Pretty much if you get anything but a class 2 or 4 Sandisk(i'd say class 4 for best of both worlds), you run a risk of an unstable system. The benchmark tests seem to put them many orders of magnitude above the higher class cards of other brands.
Plus they seem to be on special just about anywhere i've asked for them. Try radioshack if you are in the US.
I think you'll find that extensive benchmarking of a heap of cards has shown that the ones which are slow to boot are the same ones which have very low 4k random write speeds (as per monkeymike's post reference). The Sandisk 16GB Class 6 cards appear to have decent speeds for 4k random writes, ergo they will be fine to boot from. Other class 6 cards don't perform nearly as well as the Sandisk ones.
I've seen numerous benchmarks around the web showing that the Sandisk class 4's consistently match or beat the class 10's from other manufacturers and I've had great results with them in both my NC and my phones.
That said, its not going to run as well from an SD card (any sd card) as it will when properly installed as the main OS. I know this from experience. I was running CM7 from a generic class 2 for a while and it sucked. Then I got a Sandisk 16gb class 4 and that made a huge difference in usability. But over the weekend I finally took the plunge and actually installed CM7 directly on the NC-and that is a huge improvement over even the best SD card. Still, the Sandisk class 4 is a good way to test the waters.

Class 4 san disk cards are better than class 10 san disk cards for dual booting?

I was reading this forum post which claimed that a class 4 card is actually faster than a class 10 card for Cyanogenmod on the microsd card. Is that true? I currently have the 64GB san disk class 10 card (the red/grey one) as my card. It does tend to lag a bit if i'm swiping from one home screen to another. Would a class 4 card give me smoother performance?
http://forums.anandtech.com/showpost.php?p=34988392&postcount=30
If it's a Sandisk class 10, it's probably fine.
What the problem is that Sandisk's class 4 cards often perform better than the class 10 cards from other manufactures like Patriot. I have a class 4 Sandisk and a class 10 Patriot and the Sandisk is superior at 4k performance. But the class 10 Sandisk is probably fine (assuming it's a real Sandisk and not a counterfeit).
Ravynmagi said:
If it's a Sandisk class 10, it's probably fine.
What the problem is that Sandisk's class 4 cards often perform better than the class 10 cards from other manufactures like Patriot. I have a class 4 Sandisk and a class 10 Patriot and the Sandisk is superior at 4k performance. But the class 10 Sandisk is probably fine (assuming it's a real Sandisk and not a counterfeit).
Click to expand...
Click to collapse
Thanks, oh you're Ravynmagi from that same thread eh? Hahaha
Class 10 cards are best for long r/w for large files or a video camera. Most of what the tablet or phones do are shorter r/w and a class 6 or 4 will do fine or even be superior. This is particularly true for cards that are used for part of the operating system. This info was gleaned from experience with Android, NativeSD roms. If you search nativesd + hd2 there much info.
Many of the class 10 labeled cards are mislabeled anyway. A name brand like Sandisk will be more quality tested and properly labeled.
Hello guys, this is my first post here. Instead of starting a new thread, I thought it'll be appropriate to post in a thread about sd cards. I'm planning to buy microsd cards for my new Nook HD+, which is on the way. Does UHS-1 micreosd cards work with Nook HD+? I want to dual boot with cynagen mod on sd card. Which class'll be the best for running android from the sdcard? Also I want to make a back up of my Nook HD+ stock version, what size card is enough for that?
The card that I have in mind is a Strontium 16GB UHS-1 MicroSDHC Card. In its product description it says "Compatible with SDHC and SDXC host devices; not compatible with standard SD-enabled devices/readers" and "Compliant with the new UHS-I specification for ultra-high speed interfaces for SD specifications. Can only be used in UHS-I mode in UHS-I compatible devices." (I can't post link since it's my first post)
I got confused after reading that highest class won't give optimal performance. I hope some one here will help me in this. Thank you.
mashac said:
Hello guys, this is my first post here. Instead of starting a new thread, I thought it'll be appropriate to post in a thread about sd cards. I'm planning to buy microsd cards for my new Nook HD+, which is on the way. Does UHS-1 micreosd cards work with Nook HD+? I want to dual boot with cynagen mod on sd card. Which class'll be the best for running android from the sdcard? Also I want to make a back up of my Nook HD+ stock version, what size card is enough for that?
The card that I have in mind is a Strontium 16GB UHS-1 MicroSDHC Card. In its product description it says "Compatible with SDHC and SDXC host devices; not compatible with standard SD-enabled devices/readers" and "Compliant with the new UHS-I specification for ultra-high speed interfaces for SD specifications. Can only be used in UHS-I mode in UHS-I compatible devices." (I can't post link since it's my first post)
I got confused after reading that highest class won't give optimal performance. I hope some one here will help me in this. Thank you.
Click to expand...
Click to collapse
SanDisk class 4 are the best to use for everything on the HD/HD+. The device does not work reliably with faster cards.
You need about 1.5GB to do a stock backup, so a 2GB is enough.
Sent from my Nook HD+ running CM10.1 on emmc.
leapinlar said:
SanDisk class 4 are the best to use for everything on the HD/HD+. The device does not work reliably with faster cards.
You need about 1.5GB to do a stock backup, so a 2GB is enough.
Click to expand...
Click to collapse
Thanks leapinlar for that quick reply. So, a 16 or 32GB class 4 sandisk card for the dual boot and another 2GB card for the stock backup is all I need. Thanks again.
The "class' rating is only a measure of large sequential write performance, as in using it for an HD video camera. The class rating has no bearing at all on random access speeds or small reads and writes. Many sandisk class 4's have faster small random read/write performance than many class 10 cards, but its worthwhile to look at benchmarks for a card you're looking at or a list of top cards for tablet/phone usage that keys on small random read/write performance for optimal performance.
In fact, the sd card market is loaded with class 10 cards that stink at pretty much every other measure than large sequential writes.
SD cards 16G and larger are only made as class 10 devices. Properly formatting the SD card will improve it's performance.
Onageric said:
SD cards 16G and larger are only made as class 10 devices. Properly formatting the SD card will improve it's performance.
Click to expand...
Click to collapse
No they are not. Here is a 32GB class 4 SanDisk available http://www.mymemory.co.uk/Micro-SDHC/SanDisk/SanDisk-32GB-Micro-SD-(SDHC)-Card---Class-4
artesea said:
No they are not. Here is a 32GB class 4 SanDisk available http://www.mymemory.co.uk/Micro-SDHC/SanDisk/SanDisk-32GB-Micro-SD-(SDHC)-Card---Class-4
Click to expand...
Click to collapse
To be more specific - SD cards 16G and greater are manufactured to meet class 10 standards. To get the most money from their products the production line is optimized to make the fastest and most expensive product. Products that miss the QC marks for "A" grade (class 10) will/should easily pass "B" grade (class 4) specifications. The class 10 data bus can run at faster speeds than a class 4. It can also
r u n s l o w e r, meeting fully the class 4 specifications. Often manufacturers will mark their perfectly good class 10 products as class 4 to fulfill market demands. Think making money.
Onageric said:
Often manufacturers will mark their perfectly good class 10 products as class 4 to fulfill market demands. Think making money.
Click to expand...
Click to collapse
It's seems to be true. Bought "Exployd 4 class micro SD" and it's running at 10 class speed at read/write (always over 12Mb).
See this thread http://forum.xda-developers.com/showthread.php?t=1005633 for extensive discussions of comparative performance of different vendor/model SD-cards. For the purpose of running ROMs, look out for cards with high throughput in randomized read/write access, not in sequential read/write access.
FWIW, I am using exclusively Sandisk class 4, having had terrible results (lots of Wait & Force-Close) with class 10 and 6 cards from a mix of vendors.

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