[Q] SD Speed required for Data2SD

[Smii]

Hi all,

I've currently got a class 2 Samsung 4gb card that came with my Desire, and I'm looking at flashing a ROM with built-in Data2SD (Gingerburst) but before I do I want to make sure that my card is fast enough, i.e. whether I need to buy a new one.

Bearing in mind that the classes are minimum write speeds, I've just speed tested my SD card a number of times and got the follow results: (TLR, averages are at the bottom)

PC 1:
Writing speed: 4.61 MByte/s
Reading speed: 11.5 MByte/s

PC 2:
Writing speed: 4.33 MByte/s
Reading speed: 11.5 MByte/s


PC 3:
Writing speed: 4.55 MByte/s
Reading speed: 11.5 MByte/s

SD Tools 1: (Android App)
Writing speed: 5.8 MByte/s
Reading speed: 4.9 MByte/s

SD Tools 2:
Writing speed: 5.2 MByte/s
Reading speed: 4.9 MByte/s

SD Tools 3:
Writing speed: 4.6 MByte/s
Reading speed: 4.9 MByte/s

PC Average:
Writing speed: 4.49 MByte/s
Reading speed: 11.5 MByte/s

SD Tools Average:
Writing speed: 5.2 MByte/s
Reading speed: 4.9 MByte/s

Is this kind of performance acceptable for Data2SD or do I need to invest in a higher class card? And play the roulette of trying to get a brand with a decent speed record (apparently Lexar, Samsung and Sandisk are the best bets)

Thanks - your help is high appreciated!

 

[ayazora]

Based on that number, I think your microSD is a class 4.
I'm using Sandisk class 4 microSD, the benchmark speed is also around that number.
Right now I'm using A2SD+, so far so good.
I think you can use Data2SD without the need to buy a new microSD

 

[Smii]

Interesting discrepancy between the PC/SD Tools read rates - I wonder whether the reader in the PC is a bit faster there.

It's definately a class 2 card - it's printed on it!

I've been looking at (Can't post links yet, so...) Play.com - Samsung 8GB Class 6 Plus! - £11.99 because the reviews I read for Amazon Transcend 8GB Class 6 (£8.49) implied that although the price was great, it actually performed less well than an equivalent class 4 card. Apparently the Samsung at least delivers what it should do.

I guess I could just suck it and see and try a Gingerburst flash with Data2SD on my class 2 card and see how I go! If it's okay, I won't need to update...

It's my inclination that more space is nice, though. ¬_¬ Shame I don't have more cash lying around.

 

[kuldaoo]

Printed picture with class number says nothing. I have Sundisk mobile ultra with class 2 and my writing speeds are about 9MB/s (PC)...

I think your speeds are ok for desire. It will not slow your device for sure

Sent from my HTC Desire using XDA App

 

[kuraikaze]

The class number printed on the card is just a `guaranteed minimum` write speed spec.
They will often be higher, as the cards are frequently manufactured for higher nominal spec, then batch sampled/tested. If a certain percentage don't test well enough to pass class 10, for example, the whole batch will be `downgraded` and may still be more than good enough for class 4 etc.
This is much the same thing that happens with desktop CPUs, which is why some models with a stated speed have very good overclock potential.

There's also a difference between the internal data bus speeds in the phone, and running it in a PC via USB.

I recently did some comparison tests on my Desire to see if it was worth moving Dalvik cache back to internal flash, rather than SD.

Haven't got the exact figures to hand, but the internal flash runs at an equivalent of approx class 5 or 6, so any SD card in that ballpark will ensure you don't get any speed loss with Data2SD.

Even something that's right on the class 4 spec will be fine - it'd be pretty much impossible to notice any speed difference.

 

[MattBooth]

You need a class 4 at the very least to perform 720p HD recording. Most recommend a Class 6 or higher for A2SD+ and D2SD/EXT.

 

[Smii]

You need a class 4 at the very least to perform 720p HD recording. Most recommend a Class 6 or higher for A2SD+ and D2SD/EXT.

Yeah, my 720p recording skips ever few seconds. Although weirdly there have been a couple of real-world times when I've done video recording (honestly, it's not something I do very often) where 720p has been silky smooth with everything the same as it is now.

I'll see if I can pick up a decent class 6 for cheap. Trouble is I don't have a lot of money and the cheap-cheap ones get bad reviews for being sub-class 6 standard!

 

[Heisenberg]

Electronics -you get what you pay for!

Beware the cheap SD cards

Sent from my CM7.1 Desire using XDA App

 

[erklat]

Electronics -you get what you pay for!

Beware the cheap SD cards

Sent from my CM7.1 Desire using XDA App

This. You can't be a cheapskate when it comes to data storage. Saves a lot of headache down the road.