I am working on an application where I need to detect the sd card id only when the card is present on the device. I have viewed and tried this link and it solves my problem: Android get id of SD Card programmatically
But I didn't understand the exact meaning of mmcblk0 and mmcblk1, although I got that they are volume partitions of the memory.
Is anyone aware of that ? Please help if u know about the concept.
Thanks in advance !!
Here, mmcblk0 is the internal NAND, and mmcblk1 is the external sd card.
Related
I have one simple question. If i have one file in system partition of android and if i copy the same file on sdcard, which will be faster to access?
Please answer this question.
Thanks in advance
The difference will be negligible. In any case, most newer devices have just one storage onboard the device, which is partitioned. In such devices, the need to access a separate SD Card goes away, as the memory is the same as the system storage.
On devices with an SD Card, there may be a very minute delay in accessing the file, but it will be negligible in pretty much any scenario.
You will not be able to really notice the access speed difference between accessing file from internal memory and SD Card.
With internal memory you will get added advantage of a security as it won't be accessible for other applications or you cannot access it by mounting.
The answer is Internal phone memory
because disk management(for phone ) is always better for internal memory as compared to SD card, So it is faster to access internal memory but you will not be able to notice the because difference is in mili seconds
With internal memory you will get advantage like user can't see your file until unless device is not rooted.
As stated, the time difference is not noticeable. However, a simple law of physics (and EE) will tell you that the longer the distance is (in this case the I/O bus), the longer it will take in time. Thus, the SDCard is slower than anything on the motherboard, even though it is measured in miliseconds.
I have found the SDCard is best used for static storage of your media files, and apps should be installed on the phone making them run as fast as possible, even though you can move some apps to the SDCard.
The speed is not noticeable unless you are coping the very large video files. The SD card speed is measured by class like:(Class 4, 6 or 10), the class 10 have higher speed as 10MB/S and class 2 have speed around 2MB/S. So, for good class of SD card, the speed gap is less. However, normally phone memory is faster than the SD card.
I know that there are different classes of SD Cards and I also know, that there are many different kinds of internal storage (eg. my Dell Streak 5 has a 2GB Micro SD Card Class 4 built in).
However, is there a significant increase/decrease of speed if I have an app installed on a SD Card? Or is it the same (if you are not accounting the SD Classes)?
Like Phil say, it depends of a lot of factor.
I add : Your SDCard is a really important factor, you have to check your Read / Write Speed to see if the ratios are good. They depends a lot function the brand, the reference... of your SDcard.
A lot of people say it' s really faster to run on an SDCard.
Exemple here hith the CyanogenMod http://forums.androidcentral.com/barnes-noble-nook-color/85741-cm7-faster-internal-memory-sd-card-boot.html
You have to test function your hardware.
Good luck ;).
It depends.
No really, it does. The only way to be sure is to diagnose this yourself. IMHO I don't think there'll be a significant difference in speed if the circumstances are great. However, there probably are circumstances where the card could be significantly slower.
I have a requirement that I need to copy some files to the SD card programatically.
I have used
Environment.getExternalStorageDirectory()
to refer the SD card but In some devices it is referring to internal memory of the device.
Then I tried "/mnt/sdcard/" this path also still referring to Internal memory of the device.
I have done some investigation and came to know that "Environment.getExternalStorageDirectory()" will refer to internal memory of the device.
But I want to always store my files in SD card for all the devices.
I just want to know the path which should always refer to the Sd card in all the devices.
Is there any hard coded way to do this..??
Please help me.
Android doesn't know anything about the way the data is physically stored (could be a SD card, a CD, a chipset, etc). The only thing it knows is about whether the storage is "internal" or "external" (more details here).
So the way you are doing is fine: if the system gives you a path to an internal chipset when you call getExternalStorageDirectory(), this means that your physical device is built that way. There is no workaround for that.
is it possible to have low level access in Android with Java/NDK to create for example card scanner like scandisk or card defragmenter? I move a lots of stuff around my card and it gets fragmented quickly. I have experience with FAT32 defragmenting on Windows, but I'dliek to do this on Android.
Fragmentation does not affect SD card as much as it affect a harddrive since SD card does not have spinning parts or moving heads, the difference between random access vs sequential access of an SD card is negligible.
In other words, SD card does not need defragmenting; in fact defragmenting an SD card will only lower the life span of your SD card since the memory cells of an SD card have a limit on the number of read/write that you can do on them.
And if you need to "scandisk" (or "fsck" in Unix/Linux-speak, stands for "File System ChecK"), I don't think the Android's default shell comes with fsck, but you should be able to fsck the SD card from your computer.
Maybe this is related to one of my questions.
What is an effective way to determine how much free space is on the SD card?
If you just want to check it yourself, here are the steps to do it:
http://www.tech-recipes.com/rx/5641/android-how-to-check-available-internal-and-sd-card-memory-space/
UPDATE:
I just found that there is a better SO answer to this question:
How to Check available space on android device ? on SD card?
Here are some methods to get available space, these methods give you more control and you can get available space in different units bytes, kb, mb, gb.
How to Check available space on android device ? on SD card?
Usable since API level 9:
Environment.getExternalStorageDirectory().getUsableSpace();
http://developer.android.com/reference/java/io/File.html#getUsableSpace()
Here is a function that allows you to retrieve the amount of memory in the android device.
You can very easily find out the amount of memory that is left of you SD card via the phones device information. Please elaborate if your requirements are something else.
Create a file and write one byte at a time until you get an out of space exception.