Why you should format your microSD card before use

Let’s assume you just purchased a brand-new microSD card for your phone. Do you stick it inside the phone and use it straight away or do you format it before use? I’m here to tell you why you should format your microSD card before use.

Brief background

Recently, we have been talking about microSD cards and file systems.

We took a deep dive into the different microSD card formats as well as the different types of file systems.

Types of microSD cards

In the blog post, I said that there are four types of microSD cards.

  • SDSC
  • SDHC
  • SDXC
  • SDUC

SDSC and SDHC have capacities of or below 32GB and they come preformatted with FAT 32.

SDXC and SDUC however have capacities greater than 32GB and come preformatted with exFAT.

Types of file systems

The major file systems as I have also explained are

  • FAT 32
  • exFAT
  • NTFS
  • ext4
  • HFS+/APFS (if you use a Mac)

These file systems are the methods by which files are kept, arranged, and retrieved by the host computer or smartphone’s operating system.

The way I chose to arrange a house could be thought of as a file system. Now the way I would arrange a house is not the same way you would choose to arrange the very same house.

Microsoft has file systems that are compatible with their own operating systems Windows. These are FAT 32, exFAT, and NTFS. This is how they chose to arrange the house.

Other operating systems could have other ideas and they do. Linux has ext4, Apple has HFS+ and APFS and there’s also ZFS for other small operating systems. That’s not to mention SDcardFS, F2FS, YFF, etc. but I’m digressing now.

File system compatibility

Now if you enter my house and I ask you to please get me the broom. The truth is you’re going to be a little confused.

Yes. Because you obviously do not know where I have kept the broom and you wouldn’t know till I tell you exactly where to find it.

This is where certain incompatibilities between these file systems lie.

The only way for a file system built for one OS to work on another OS is for the companies to exchange information that would help their OS read a different file system.

So I could tell you that the broom is in the kitchen, whereas in your own house, you may keep it in a broom closet or perhaps in the corridor.

Giving you that information shows you where to find stuff in my house. This is how different OS can support file systems other than their own.

Now FAT32 is supported by nearly every OS around today.

exFAT only enjoys that privilege to an extent. This is because Microsoft has patents that have mostly discouraged Linux from officially developing full compatibility for it.

File systems supported by Android

Android is a Linux-based operating system. In fact, the kernels (or codes) that sit at the base of Android that transmit information from software to your phone’s hardware are purely Linux.

So the file system that your Android phone natively supports is Linux-based and the file system designed for Linux is ext4.

As you can see, most of the disk partitions on my phone are formatted in ext4.

Moving further, Android has a File system that it uses for the internal storage partition that you can access.

This is called F2FS.

It was designed by Samsung way back for TouchWiz. Google as usual borrowed it and added it to AOSP for everyone to use. With Samsung’s permission of course.

Google uses SDcardFS to manage the files in the F2FS partition that is available to you the user.

Now as you can quite clearly see, Android has a whole ass ecosystem of its own.

MicroSD cards and Android

When you introduce a microSD card that was formatted with Windows-based file systems into Android, you may run into some issues along the line.

This is especially true for SDXC cards that are well over 32GB and come preformatted with exFAT.

With older SDHC microSD cards pre-formatted with FAT32, there should be zero issues because Linux has full support for FAT32.

So if Linux has full support for FAT32, you can be sure that Android has full support as well.

Why you should you format your microSD card before use

exFAT on the other hand is a different matter. Although Android should support exFAT and it does. The support is not completely official. So there may be some missing codes or other stuff that could later cause errors on your microSD card.

This is why when you insert a new SD card into a phone, most phones will demand that you format the card first.

This is because Michael may not understand how John arranged a house. To make things easier, he (Michael) may want to arrange the house in a way that he understands. Android does this by formatting the microSD card.

Now when you format a card, you do not just wipe its contents. You’re rewiring the file system on that card. The whole thing.

But a lot of us tend to ignore the prompt format. I did it too and paid for it with all my files ๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚. Books that I’ll never get back, pictures that I’ll never see again.

Another thing to note is that Android is always changing, always updating, always improving but the SD card you just bought may have been sitting on a shelf for years.

Its preformatted file system may lack some stuff that Android has. To avoid problems, android may format the card to its type of filesystem that is 100% compatible.

So to answer the question of if you should format a new microSD card…

If it’s an older SDSC or SDHC card with FAT32, you may not need to format it, unless, of course, your phone prompts you to.

If you are using an SDXC or SDUC card over 32GB like a 64GB, 128GB, or even 512GB, whether your phone prompts you or not. Please format it. It would save you a lot of headaches in the long run.

Also, note that you should never remove your microSD card from your phone while it is on without unmounting it first.

It may sound pedantic but it’s rather very important. I see people doing it all the time thinking that it’s not important. It could cost you your files. So that’s why you should format your microSD card before use.


Thank you for reading to the end. As always, ensure to check out our links for more information

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