Android Enthusiasts Stack Exchange is a question and answer site for enthusiasts and power users of the Android operating system. It only takes a minute to sign up.
Sign up to join this community
Sometimes my SD card gets "corrupted" and this leads to many read/write errors. Usually, connecting the SD card to the windows 7 and selecting the "Error Checking" (Right click the drive > Tools > Error Checking) option finds the corruption and fixes it.
How do I check SD cards for drive errors and fix the same from within the android itself?
I'd also like to mention that I'm on rooted froyo with busybox installed.
You can fix this with the help of root and a terminal emulator (e.g. Android Terminal Emulator (or, alternatively, using adb shell). The binary to do the job is called fsck, and usually located in either /system/xbin or /system/bin. Sometimes you need a special variant of it, which might e.g. be called fsck.exfat or the like. So first let's make sure we find the right binary:
cd /system/xbin
ls fsc*
If not found, repeat with /system/bin. I will assume here it was found in the first place, and is simply called fsck (adjust the following correspondingly if that's not the case).
As fsck comes from the "Linux core", we can consult its man page for the syntax. Though there might be some options not working on Android, the most basic ones should. See the linked man page for details (or run a Linux VM and use man fsck in case that page disappears) -- I will stick to the basics here:
First we need to find the device your SD card is bound to. If it's mounted, the mount command will assist us:
mount
That's it, basically: Check the output and see where your SD card sits. Usually this is something using vold, but it's different between devices. Output may include something like /dev/block/vold/179:17 on /mnt/storage/sdcard -- in that case, the first part of my quote is our device. In order to repair the "drive", you need to unmount it first. This can be done via the settings menu, or, as we're just in the terminal, by issuing
umount /dev/block/vold/179:17
Now we can go for the repair job. Basic syntax is:
fsck [options] [-t fstype] <filesystem> [fsoptions]
So we first try the simplest approach and hope fsck figures out everything itself:
fsck -C -r /dev/block/vold/179:17
Which basically means: Show progress (-C), and always ask the user to repair (-r) any errors on /dev/block/vold/179:17. If this does not work out, check with the linked man page for further options.
cd steps if you want by using ls /system/bin/fsc* and ls /system/xbin/fsc* from whatever your current working directory is. You could even combine the two into one command with ls /system/xbin/fsc* /system/bin/fsc*.
Jan 31, 2013 at 16:52
umount, do you have to be root?
Dec 26, 2016 at 13:35
/dev) that way.
While other answers are correct (at least partially), just to add some extra notes. On recent Android releases you don't need to run filesystem check manually as vold handles this automatically. See When should I run a consistency check on my removable MicroSD card?
If you want to do this manually, you need a rooted device because it's not possible to access block devices on un-rooted devices. Also you need to un-mount the filesystem before checking for errors. Since Android 6 external SD card is mounted at /mnt/media_rw/[UUID] and then emulated on /mnt/runtime/[VIEW]/[UUID]. A VIEW is then bind-mounted to /storage/[UUID]. See details in How to save files to external SD card?.
After un-mounting SD card fully, run respective fsck.* binary on the block device. Usually init enumerates SD card block device as /dev/block/mmcblk1p* (p* denotes partition number, usually it's only 1) while vold creates another device node in /dev/block/vold/[MAJOR:MINOR]. You need to find the correct block device (may also check by mount | grep /mnt/media_rw before un-mounting filesystem).
For FAT[N] family of filesystems you can use fsck_msdos (or fsck.fat), and fsck.exfat for exFAT. If these aren't built with your ROM (exFAT was closed source until recently, so there could be license issues), you can use external binaries. Or build from (dosfstools or exfat) source code.
To run filesystem check:
~# fsck.exfat /dev/block/mmcblk1p1
thank for this, it saves my day :)
root@android:/ # mount | grep -i sdcard
/dev/block/nandk /mnt/sdcard vfat rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp437,iocharset=ascii,shortname=mixed,errors=remount-ro 0 0
root@android:/ # /system/bin/fsck_msdos -y /dev/block/nandk
I've found an app called AParted on the market that can "repair some damaged sdcard and scan for bad blocks" etc.
If I'm not mistaken you can force Android to fsck both the internal and external storage on reboot by doing the following depending on your ROM.
run terminal app and type
su
touch /forcefsck
Then reboot.
If your phone is not rooted, this will definitely fail.
fsck actually ran or not?
Dec 14, 2015 at 8:12
touch /forcefsck will only work on a device with an init script which checks for the presence of a /forcefsck file. I don't know of one single Android device which has such an init script. So, although your technique will likely work on Debian, Ubuntu, and Mint devices, I highly doubt that it will work on any Android device. If anyone ever finds even one single Android device with an init script which checks for /forcefsck, please let me know! Simply reply to this comment.
Jun 3, 2016 at 15:00