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MicroSD card question

QueBert

QueBert

Lifer
I'm going to get a 32gb card for my Galaxy Note, I see the class 4 and ultra class 6. I'm not sure if the phone can even take advantage of the faster read speeds of the class 6. I'll be putting a lot of 720p video on my phone. The only comparison I found on XDA the guy said the class 4 was faster than the 6 or 10 for him which doesn't make any sense to me.
 
OILFIELDTRASH said:
I'm using a class 4 in my note and never noticed the slightest bit of lag.
Are you use to the size yet?
Click to expand...

Do you have any 720p video on it? And yeah I'm use to it, the size adjustment period for me was actually a lot faster than I thought it would be. I can't use it one handed, but I didn't expect to be able to.
 
QueBert said:
I'm going to get a 32gb card for my Galaxy Note, I see the class 4 and ultra class 6. I'm not sure if the phone can even take advantage of the faster read speeds of the class 6. I'll be putting a lot of 720p video on my phone. The only comparison I found on XDA the guy said the class 4 was faster than the 6 or 10 for him which doesn't make any sense to me.
Click to expand...

Remember that "class" for SD cards denote minimum transfer speeds, not average or maximum. Also, not all SD cards are built the same, similar to USB flash drives, so I wouldn't buy the cheapest micro SD card you can find.
 
When you use a microSD/SDHC/SDXC card in an android device, there are 2 factors that you have to consider:

- sequential write
- random 4k write

Sequential write is obvious (Class 4 = minimum 4MB/s sequential write, Class 6/10 = etc..). Copy large files to the card is where you'll see your limitation

However, there is random 4k write. If you plan on running anything off the SD (app storage, app cache, etc..) then this is very, very important.
For MicroSD cards:
- most Class 4, 1/2 of the Class 6 cards, and very few Class 10 cards will do random 4k write at around ~1.5MB/s. it sounds slow, but its good enough for most applications
- most Class 10 cards will have a random 4k write of about ~0.01MB/s (that is not a typo). That means that most Class 4 micro cards are theoretically 150x faster than most Class 10 micro cards.

There is a new breed of high speed Class 6/Class 10 micro cards that have great sequential write ( > 10MB/s) AND great random4k write (> 1.5MB/s)

So far the only cards that I would personally recommend:
- the Samsung High Speed Class 10 32GB MicroSDHC, which gets 13MB/s sequential write and 1.5MB/s random 4k write (note, do NOT GET THE PLUS VERSION). The Plus version has 0.01MB/s random 4k write, but around 16MB/s sequential write.
- the SanDisk Mobile Ultra Class 6 30MB/s Series (32GB MicroSDHC or 64GB MicroSDHC). Even though its only Class 6, it can routinely get around 9.5MB/s sequential write, and 1.5MB/s random 4k write.

Hope this helps!
 
AkumaX said:
When you use a microSD/SDHC/SDXC card in an android device, there are 2 factors that you have to consider:

- sequential write
- random 4k write

Sequential write is obvious (Class 4 = minimum 4MB/s sequential write, Class 6/10 = etc..). Copy large files to the card is where you'll see your limitation

However, there is random 4k write. If you plan on running anything off the SD (app storage, app cache, etc..) then this is very, very important.
For MicroSD cards:
- most Class 4, 1/2 of the Class 6 cards, and very few Class 10 cards will do random 4k write at around ~1.5MB/s. it sounds slow, but its good enough for most applications
- most Class 10 cards will have a random 4k write of about ~0.01MB/s (that is not a typo). That means that most Class 4 micro cards are theoretically 150x faster than most Class 10 micro cards.

There is a new breed of high speed Class 6/Class 10 micro cards that have great sequential write ( > 10MB/s) AND great random4k write (> 1.5MB/s)

So far the only cards that I would personally recommend:
- the Samsung High Speed Class 10 32GB MicroSDHC, which gets 13MB/s sequential write and 1.5MB/s random 4k write (note, do NOT GET THE PLUS VERSION). The Plus version has 0.01MB/s random 4k write, but around 16MB/s sequential write.
- the SanDisk Mobile Ultra Class 6 30MB/s Series (32GB MicroSDHC or 64GB MicroSDHC). Even though its only Class 6, it can routinely get around 9.5MB/s sequential write, and 1.5MB/s random 4k write.

Hope this helps!
Click to expand...

Helps tons, the Samsung looks great, I was looking at the Sandisk but the Samsung seems to be all around faster and it's only a few bucks more than the Sandisk.
 
AkumaX said:
When you use a microSD/SDHC/SDXC card in an android device, there are 2 factors that you have to consider:

- sequential write
- random 4k write

Sequential write is obvious (Class 4 = minimum 4MB/s sequential write, Class 6/10 = etc..). Copy large files to the card is where you'll see your limitation

However, there is random 4k write. If you plan on running anything off the SD (app storage, app cache, etc..) then this is very, very important.
For MicroSD cards:
- most Class 4, 1/2 of the Class 6 cards, and very few Class 10 cards will do random 4k write at around ~1.5MB/s. it sounds slow, but its good enough for most applications
- most Class 10 cards will have a random 4k write of about ~0.01MB/s (that is not a typo). That means that most Class 4 micro cards are theoretically 150x faster than most Class 10 micro cards.

There is a new breed of high speed Class 6/Class 10 micro cards that have great sequential write ( > 10MB/s) AND great random4k write (> 1.5MB/s)

So far the only cards that I would personally recommend:
- the Samsung High Speed Class 10 32GB MicroSDHC, which gets 13MB/s sequential write and 1.5MB/s random 4k write (note, do NOT GET THE PLUS VERSION). The Plus version has 0.01MB/s random 4k write, but around 16MB/s sequential write.
- the SanDisk Mobile Ultra Class 6 30MB/s Series (32GB MicroSDHC or 64GB MicroSDHC). Even though its only Class 6, it can routinely get around 9.5MB/s sequential write, and 1.5MB/s random 4k write.

Hope this helps!
Click to expand...

Right. To simplify:

Classes measure sequential write speeds, which can be boosted but sacrifice random write speeds.
 
QueBert said:
Helps tons, the Samsung looks great, I was looking at the Sandisk but the Samsung seems to be all around faster and it's only a few bucks more than the Sandisk.
Click to expand...

Hehe yeah, just trying to help the Sequential Write VS Random 4K Write debate 😛

The upside to the new SanDisk Mobile Ultra 30MB/s Class 6 is that it can actually do +35MB/s sequential read in a USB 3.0 card reader (in a USB 2.0 port or USB 3.0 port!)
 
Yeah this is a problem when it comes to swapping out the internal cards on WP7 devices since they require good Random speeds (or else your device goes sloooooooooooow). Good explanation, thanks!
 
AkumaX said:
So far the only cards that I would personally recommend:
- the Samsung High Speed Class 10 32GB MicroSDHC, which gets 13MB/s sequential write and 1.5MB/s random 4k write (note, do NOT GET THE PLUS VERSION). The Plus version has 0.01MB/s random 4k write, but around 16MB/s sequential write.
- the SanDisk Mobile Ultra Class 6 30MB/s Series (32GB MicroSDHC or 64GB MicroSDHC). Even though its only Class 6, it can routinely get around 9.5MB/s sequential write, and 1.5MB/s random 4k write.
Click to expand...

Hi, how about a 8-16 GB micro sd with decent random write speed ?
Do you have any recommendation ?😉
 
dguy6789 said:
Do the 64 gig cards work in all of the current phones?
Click to expand...
64 GB cards are SDXC. SDXC is not supported on some devices. Some only list SDHC support, which maxes out at 32 GB. That said, some devices which only list SDHC support actually do support SDXC if formatted to FAT32.

WelshBloke said:
I think they work in all GB and ICS Android ones.
Click to expand...
Are you sure?

I note that there are a few Windows computers with built-in SD slots that don't work with SDXC at all, despite the fact that Windows supports SDXC (and of course exFAT) just fine. The same goes with some SD readers.

WelshBloke said:
You just have to let the phone format the card to FAT32 rather than exFAT.
Click to expand...
As an aside... Not so much for phones, but for tablets, many support NTFS now. Not Google's Nexus 7 though. Same goes for some Blu-ray players that have AVI and MKV support.

I think I'd personally just prefer official SDXC and exFAT support though, since my Macs only have read-only NTFS support. They have full read/write support for exFAT though.
 
Last edited:
AkumaX said:
When you use a microSD/SDHC/SDXC card in an android device, there are 2 factors that you have to consider:

- sequential write
- random 4k write

Sequential write is obvious (Class 4 = minimum 4MB/s sequential write, Class 6/10 = etc..). Copy large files to the card is where you'll see your limitation

However, there is random 4k write. If you plan on running anything off the SD (app storage, app cache, etc..) then this is very, very important.
For MicroSD cards:
- most Class 4, 1/2 of the Class 6 cards, and very few Class 10 cards will do random 4k write at around ~1.5MB/s. it sounds slow, but its good enough for most applications
- most Class 10 cards will have a random 4k write of about ~0.01MB/s (that is not a typo). That means that most Class 4 micro cards are theoretically 150x faster than most Class 10 micro cards.

There is a new breed of high speed Class 6/Class 10 micro cards that have great sequential write ( > 10MB/s) AND great random4k write (> 1.5MB/s)

So far the only cards that I would personally recommend:
- the Samsung High Speed Class 10 32GB MicroSDHC, which gets 13MB/s sequential write and 1.5MB/s random 4k write (note, do NOT GET THE PLUS VERSION). The Plus version has 0.01MB/s random 4k write, but around 16MB/s sequential write.
- the SanDisk Mobile Ultra Class 6 30MB/s Series (32GB MicroSDHC or 64GB MicroSDHC). Even though its only Class 6, it can routinely get around 9.5MB/s sequential write, and 1.5MB/s random 4k write.

Hope this helps!
Click to expand...
What software were you using for speed testing, Crystal Disk Mark? I just ordered a Patriot 32 GB Class 4 microSD (PSF32GMCSDHC43P), simply because it was inexpensive at 10 bux. Hopefully the random 4K write isn't absolutely terrible, but since I'll be using it mainly for viewing transferred videos, I suspect the sequential write will be more relevant. I am guessing it will bench around 4 MB/s given its cost.
 
Last edited:
Eug said:
What software were you using for speed testing? I just ordered a Patriot 32 GB Class 4 microSD (PSF32GMCSDHC43P), simply because it was inexpensive at 10 bux. Hopefully the random 4K write isn't absolutely terrible, but since I'll be using it mainly for viewing transferred videos, I suspect the sequential write will be more relevant. I am guessing it will bench around 4 MB/s given its cost.
Click to expand...

http://forums.anandtech.com/showthread.php?t=2226355&highlight=sandisk
CrystalDisk.
 
Hey, not bad. I was going to get a cheap 32 GB microSD card for my Nexus 7, but it turns out the USB reader + microSD was no smaller than a small USB drive, so I just got a 64 GB USB drive instead, the Patriot Axle.

250.jpg


It gets 20 MB/s sequential as claimed for writes (and 23 MB/s for reads). That's in FAT32, but NTFS is slower at 11 and 22 respectively. However it also gets around 5 MB/s or more for 4k random read and 0.8 MB/s for 4k random writes (both in FAT32 and NTFS).

That is way, way, way better than what my 32 GB Corsair Voyager mini gets 6 MB/s or so for sequential writes and 0.06 MB/s for random writes in FAT32 (or half that random write speed with NTFS). Ouch.
 
i just bought three 8gb sandisk class 4 cards off ebay for $15 total for all three. they are nearly 5mb/sec write and they max out the usb for read which is like 11mb/sec

very happy with them, i love sandisk cards
 
Eug said:
Hey, not bad. I was going to get a cheap 32 GB microSD card for my Nexus 7, but it turns out the USB reader + microSD was no smaller than a small USB drive, so I just got a 64 GB USB drive instead, the Patriot Axle.

250.jpg


It gets 20 MB/s sequential as claimed for writes (and 23 MB/s for reads). That's in FAT32, but NTFS is slower at 11 and 22 respectively. However it also gets around 5 MB/s or more for 4k random read and 0.8 MB/s for 4k random writes (both in FAT32 and NTFS).

That is way, way, way better than what my 32 GB Corsair Voyager mini gets 6 MB/s or so for sequential writes and 0.06 MB/s for random writes in FAT32 (or half that random write speed with NTFS). Ouch.
Click to expand...

Cool! Last Patriot USB I had only did ~5MB/s write. Didn't even check for Random 4k speeds since I knew that I wasn't going to use a slow drive like this for anything more important than storing MP3s/movies.

That's quite a fast 64GB you have then, 23MB/s read | 20MB/s write is pretty darn good.

My latest "exploration" was a new Sony 32GB SDHC UHS-I card. Paired up with my USB 3.0 card reader/port, I was able to achieve 84MB/s read | 47MB/s write 😱
 
a) The phone can take advantage of faster speeds ?
b) What sort of app do you have that requires the faster speed ?
-
I suppose if you take a lot of pictuers very quickly you might notice the difference; class 4 are generally fast enough for taking 1080p videos (which generally ahve a bit rate of 4 or 5 mb/s (class 4 are 32mb/s); high end consumer and professional 1080p videos can be 70-80mb/s; but phones tend to use a lower bit rate.
-
I use class 4 for my tablets (to watch 720p videos); but I have to admit it takes less time to copy a 3GB file to a class 10 card; I also use class 10 (or better) for digital cameras.
 
AkumaX said:
Cool! Last Patriot USB I had only did ~5MB/s write. Didn't even check for Random 4k speeds since I knew that I wasn't going to use a slow drive like this for anything more important than storing MP3s/movies.

That's quite a fast 64GB you have then, 23MB/s read | 20MB/s write is pretty darn good.

My latest "exploration" was a new Sony 32GB SDHC UHS-I card. Paired up with my USB 3.0 card reader/port, I was able to achieve 84MB/s read | 47MB/s write 😱
Click to expand...
I don't think the Patriot Axle is exactly "fast" in the greater scheme of flash drive things, but it's certainly not anywhere near as slow as I was expecting something as tiny as this. (I bought it mainly for the size and cost - $35 for 64 GB.) BTW, here is someone's bench of the 32 GB model:

axle32gb.png


For some reason he's getting horrible 4K write speeds. Mine was something like 90X as fast, at over 0.8 MB/s. He seems to be using an older version of Crystal Disk Mark, but that shouldn't matter. He's using 100 MB though, whereas I was using the default 50 MB. Or maybe the 64 GB like I got is just inherently faster.

P.S. For NTFS, any recommendations for allocation unit size? I've been using 4096.
 
Last edited:
"... That means that most Class 4 micro cards are theoretically 150x faster than most Class 10 micro cards [on random write speeds]."

I registered for the purpose of thanking you for your super helpful post. I was wondering whether I had two defective class 10 cards, because my SanDisk class 4 blows them both away on random write speeds. As a result it's WAY faster running portable apps. My 8GB SanDisk class 4 gets (per CrystalDiskMark) 512k random write of 3.3 MB/s, 4k random write 1.3 MB/s, and 4K QD32 random write of .9 MB/s. That's many multiples faster than my class 10 cards' random write speeds.
So again, thanks! Now I know what's going on.
 
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