MicroSDHC Class?
 

I see class 2 and class 6 16GB MicroSDHC cards available. Nokia seems to be selling a class 2 device as an accessory for the N900, but wouldn't a class 6 - with 40x versus 13x transfer rate - be better? Or would the N900 hardware anyway not be able to use this speed?

Re: MicroSDHC Class?
 

Hmm ideally it should. But for accessing most files I don't think it makes a difference. Now if you were to be booting off the SDHC card it would.

Re: MicroSDHC Class?
 

Unless you're doing something that operates at a high bitrate, such as video, 2x is plenty.

Re: MicroSDHC Class?
 

I wonder what speed rating the 32GB on-board MMC device has. Anyone know?

Re: MicroSDHC Class?
 

For the same price as class 2 get class 6 off of newegg--thats where I got mine.

Re: MicroSDHC Class?
 

Well, that's only SD. We're talking MicroSD, and that's only available in 16gb right now.

Re: MicroSDHC Class?
 

I'm talking about the same thats why I posted, it's a microSDHC 16GB the biggest version you can buy till Sandisk comes out with the 32GB version either later this year or early next year.

http://www.newegg.com/Product/Produc...-245-_-Product

^^ This sale usually happens with this product about every six weeks, it's normal price is around $60.

Compared with the Class 2 Nokia is selling on there website for $79.95. I'll take the one off of newegg with class 6.
http://www.nokiausa.com/find-product...dhc-card-mu-44

If you don't like Ridata there are four other manufacturers w/class 6 all under $60.

Re: MicroSDHC Class?
 

Well, I'd love a 16gb and a 32gb microsd. But for now I'm waiting until the 32 comes out so that the 16 becomes a reasonable price. $40+ is still way to much money for me right now.

Re: MicroSDHC Class?
 

I read somewhere on engadet ( I'll find the link later today ) that Sandisk is going to initially release it in class 2 & 4 and hopefully down the road a class 6.

32GB micro sdhc class 6 makes me feel all warm and fuzzy...

Re: MicroSDHC Class?
 

Well, given recent news that Western Digital just bought them, we might see that happen really soon, or we may not for ages, if ever. I like WD, but I don't like the idea they bought Sandisk. It gives them far too much control of the flash storage market, especially since Sandisk already holds an iron grip on it. There's also the fact that everything is moving to flash storage, which creates an even more frightening scenario. >.<

Re: MicroSDHC Class?
 

i've heard differing opinions on this - i asked the question regarding the OMNIA HD, which i was told that CLASS 2 was ok even for HD playback, maybe an issue for recording though..

Re: MicroSDHC Class?
 

Playback isn't as intensive as recording. Where class shines is the writing speed (though of course it's also faster at reading). Things like recording something, or swap on the tablet, something that involves writing to the flash memory would benefit the most from a higher speed class.

Re: MicroSDHC Class?
 

16GB class 2 will take a few hours to load if you're loading up the entire thing...

Re: MicroSDHC Class?
 

Just thought i'd start this thread up again now that the lucky 300 have N900's to play with.
Has anyone noticed any dropped frames when capturing video, or similar problems when using a class 2 card? If so, did using a faster (i.e. higher class) card correct it?
Thanks for any info. Just wanted to check that my current class 2 card isn't going to be a bottleneck in the N900 hardware.

Re: MicroSDHC Class?
 

I'm wondering about the recommended SD Class, too. At what point does the hardware become the bottleneck vs the speed class of the SD Card?
8GB class 4 & 6 are commonly available. I've seen Class 8, but rarely. Unless I hear otherwise, I'll likely get Class 6.
Any issues with SanDisc compatibility? There was a thread discussing N810 issues reading SanDisc SD cards.
Steve

Re: MicroSDHC Class?
 

Looks like more people have received their N900s.

Any word on whether the N900 will fully utilize the speed advantage of a Class 6 Micro SDHC card? Or does the N900 bottleneck the card and if so, which class is the cutoff performance-wise?

Re: MicroSDHC Class?
 

I have a SanDisk class 6 8GB in my N900, need a way to test it. dd?

Re: MicroSDHC Class?
 

well a very informal test:

dd if=/dev/zero of=test.dat bs=1024 count=100000

took 20 seconds to create a 102,400,000 byte file.

Re: MicroSDHC Class?
 

Class 2 means it can do at least 2MB/sec read/write,
Class 4 means it can do at least 4MB/sec read/write.
Class 6 means it can do at least 6MB/sec read/write.

http://www.sdcard.org/developers/tech/speed_class/

But most Class 2 cards can easily do at least 6MB/sec these days.
My Class 4 Sandisk card can do 14MB/sec write and 18MB/sec read.
My vanilla Class 2 Sandisk can do 7MB/sec write and 12MB/sec read.
My no name Class 4 card can do around 12MB/sec both read/write.
(At the end, pretty much ALL cards meet Class 4 and most exceed Class 6 even if it say sit's Class 2)

So.... These 'low' Class 2/4/6/ values are completely useless....

Another example:
- 1080p AVCHD video records at up to around 25Mb/sec in most HDvideo cameras. (Note the small "b" for bit) So that's around 3MB/sec (big "B" is Byte). It would be extremely difficult to even find a card that cannot do 3MB/sec. Even the dodgy ebay ones included.

So these days, unless you want SUPER fast card to be used with a SUPER fast card reader to do more than 20MB/sec, you don't need to worry about "Class" specification as nearly ALL cards these days are at least as fast as Class 6 specifications in almost all cases. (Except for maybe dodgy ebay fake cards)

It's just that there are cards which are MUCH faster than Class 6 and there are cards that are just a little bit faster than Class 6. But those who have such high requirement should know about this already and buy the appropriate high-end cards that promise that specific speed accurately and have the equipment capable of taking advantage of such speed. (eg. Expensive memory card reader and fast DSLR etc)

Re: MicroSDHC Class?
 

Can anyone test the internal memory (MyDocs) vs. a class 6 microSD? I want to confirm my suspicions.

Re: MicroSDHC Class?
 

The class of a SDHC card means minimum write speed based on "the best fragmented state where no memory unit is occupied". Try also with many small files for instance.

Re: MicroSDHC Class?
 

guys, now that you're on this subject, i have a noob question... is there any substantial difference of battery use if the microSD is class 2 or 6?

Re: MicroSDHC Class?
 

There's an article comparing Class 2 and Class 6 cards here:
http://thenokiaguide.com/2010/10/15/...-16gb-class-6/

Class 6 card is clearly faster when copying files to/from a computer using USB. Does it actually reflect the way N900 accesses a memory card or is it irrelevant here?

I know that this question has already been asked but I don't think it has been answered - I was wondering if it makes any sense buying Class 6 or 10 cards for N900? Does anyone know what is the maximum speed N900 can read/write from/to a memory card?

Re: MicroSDHC Class?
 

x2, this is an excellent question.

Re: MicroSDHC Class?
 

how do i find Class of my card.. Which am holding it right not with out reading its package.. ;) Which i have dumped it years ago :D

Re: MicroSDHC Class?
 

Yes, it does. You can look into my measurement here - http://talk.maemo.org/showpost.php?p...0&postcount=91

Re: MicroSDHC Class?
 

You can keep an eye on this thread and see whether more people post their results:

MicroSD benchmark

Re: MicroSDHC Class?
 

cpitchford [discussions.nokia.co.uk]:

the microSDHC cards still a bottleneck generally, even the class 10 (although he quotes only class 4 numbers).

class 10 benchmarks by JayBEE [tmo]:

Patriot Class 10 8GB
Read: 14.0621 MB/s
Write: 11.4785 MB/s

comment by aligatro re Meego 1.1:

It lagged like hell on class 6 card.

but a real-world comparison between class 6 and class 10 on n900 running meego; couldn't find one. if the primary use case is dual booting meego, then choosing between, for example, verbatim 4gb class 6 at 11€ and kingston 16gb class 10 at 80€ is not that easy.

Re: MicroSDHC Class?
 

The choices like that are never easy :) I believe the sweet spot for Class 6 micro sd cards is 8gb at the moment as they go for around £12-14 in UK. Whether they perform better than this:

My result
SanDisc Class2 16GB
Read: 14.5952 MB/s
Write: 8.53831 MB/s

that's a completely different story.

(NOTE: they are not my results - it was copied from the benchmark thread). Thanks for the links guys!

Re: MicroSDHC Class?
 

Class rating and these benchmarks test the single stream sequential write and read speed. In real life, access patterns are more random. It's theoretically entirely possible that a class 4 card could slow down to 1M/s and a class 10 card could slow down to 0.1M/s, depending on how they're designed and built, which would result in the class 4 feeling faster in MeeGo.

Generally higher class rating does mean faster speed under most loads, but you shouldn't be surprised when you find exceptions.

For digital camera use, the class rating is the most useful, because it's the access pattern of a dedicated purpose-built camera that the class rating targets.

Re: MicroSDHC Class?
 

It depends what you want to use the card for. If it's just data storage like music and movies then the class probably doesn't matter much. But if you want to boot MeeGo or Android off it, then it matters a great deal.

Re: MicroSDHC Class?
 

Indeed. For storage of data even a low class rating is sufficient: sustained bandwidth when playing even a 720p video is about 800kb/s, way below even class 2 card. However, if the media is used for reading and writing lots of random data then higher class rating will obviously increase performance. When booting a full OS from such a media it becomes even more important.

Re: MicroSDHC Class?
 

I see edgar2 quoted my sdbench results from the other thread. My sole intent on getting a sd card was to run/test MeeGo 1.1 on my N900. I read it was recommended to get a fast sd card to do this so I went to Fry's and saw they had Patriot Class10 4GB & 8GB cards for $15 and $25 respectively so I purchased the 8GB. I was also thinking that I may go for a triple-boot scenario (Maemo, MeeGo, & NitDroid) if/when that becomes possible. My hope is that Qt makes it to both iOS and Android and the ability to switch between the 3 would give me the ideal setup for testing my apps.

I must say, MeeGo 1.1 runs quite well for me! Bring on the ability to triple-boot!

Re: MicroSDHC Class?
 

Years ago, you say? If you don't see the classification on the card and it's years old as you stated, you may have what is considered Class 0.

FWIW, read http://en.wikipedia.org/wiki/Secure_Digital