I overclocked my raspberry pi 2 myself yesterday. However I also increased the sd_freq. Now after a reboot my microsdcard is mounted as read only. I have a laptop with linux installed where I can try to repair it.Here is fsck:fsck /dev/sdb6fsck von util-linux 2.25.1e2fsck 1.42.10 (18-May-2014)fsck.ext2: Datei oder Verzeichnis nicht gefunden beim Versuch, /dev/sdb6 zu ffnenIst das Gert mglicherweise nicht vorhanden?That's german. The translation of that is:File or directory not found. Failed to open /dev/sdb6Does the device exist?However if I run dmesg, I know that the laptop sees the microsdcard with  errors:    [ 2927.961523] JFS: nTxBlock = 8192, nTxLock = 65536[ 2928.079252] ntfs: driver 2.1.31 [Flags: R/O MODULE].[ 2928.297070] QNX4 filesystem 0.2.3 registered.[ 2928.459834] raid6: mmxx1      346 MB/s[ 2928.516455] raid6: mmxx2      679 MB/s[ 2928.573186] raid6: sse1x1     114 MB/s[ 2928.630046] raid6: sse1x2     191 MB/s[ 2928.686624] raid6: sse2x1     175 MB/s[ 2928.743233] raid6: sse2x2     343 MB/s[ 2928.799919] raid6: int32x1    171 MB/s[ 2928.856656] raid6: int32x2    240 MB/s[ 2928.913079] raid6: int32x4    282 MB/s[ 2928.969883] raid6: int32x8    269 MB/s[ 2928.969891] raid6: using algorithm mmxx2 (679 MB/s)[ 2928.969896] raid6: using ssse3x1 recovery algorithm[ 2928.997412] xor: measuring software checksum speed[ 2929.029731]    pIII_sse  :  4652.400 MB/sec[ 2929.063063]    prefetch64-sse:  5186.400 MB/sec[ 2929.063071] xor: using function: prefetch64-sse (5186.400 MB/sec)[ 2929.319852] Btrfs loaded[ 2929.678921] EXT4-fs (sda2): unable to read superblock[ 2929.685504] EXT4-fs (sda2): unable to read superblock[ 2929.692989] EXT4-fs (sda2): unable to read superblock[ 2929.699864] FAT-fs (sda2): invalid media value (0x39)[ 2929.699876] FAT-fs (sda2): Can't find a valid FAT filesystem[ 2929.720715] XFS (sda2): Invalid superblock magic number[ 2929.733631] FAT-fs (sda2): invalid media value (0x39)[ 2929.733643] FAT-fs (sda2): Can't find a valid FAT filesystem[ 2929.752486] MINIX-fs: unable to read superblock[ 2929.789860] attempt to access beyond end of device[ 2929.789873] sda2: rw=16, want=3, limit=2[ 2929.789883] hfsplus: unable to find HFS+ superblock[ 2929.798484] qnx4: no qnx4 filesystem (no root dir).[ 2929.804082] ufs: You didn't specify the type of your ufs filesystemmount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ...>>>WARNING<<< Wrong ufstype may corrupt your filesystem, default is ufstype=old[ 2929.816251] hfs: can't find a HFS filesystem on dev sda2[ 2932.646443] audit: type=1400 audit(1430243601.363:38): apparmor=STATUS operation=profile_replace name=/usr/sbin/ntpd pid=24052 comm=apparmor_parser[ 2947.369673] audit: type=1400 audit(1430243616.083:39): apparmor=STATUS operation=profile_replace name=/usr/sbin/tcpdump pid=27551 comm=apparmor_parser[ 2993.836057] EXT4-fs (sda2): unable to read superblock[ 2993.842237] EXT4-fs (sda2): unable to read superblock[ 2993.849180] EXT4-fs (sda2): unable to read superblock[ 2993.856179] FAT-fs (sda2): invalid media value (0x39)[ 2993.856192] FAT-fs (sda2): Can't find a valid FAT filesystem[ 2993.876759] XFS (sda2): Invalid superblock magic number[ 2993.890830] FAT-fs (sda2): invalid media value (0x39)[ 2993.890849] FAT-fs (sda2): Can't find a valid FAT filesystem[ 2993.907427] MINIX-fs: unable to read superblock[ 2993.913828] attempt to access beyond end of device[ 2993.913841] sda2: rw=16, want=3, limit=2[ 2993.913851] hfsplus: unable to find HFS+ superblock[ 2993.920820] qnx4: no qnx4 filesystem (no root dir).[ 2993.926967] ufs: You didn't specify the type of your ufs filesystemmount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ...>>>WARNING<<< Wrong ufstype may corrupt your filesystem, default is ufstype=old[ 2993.940394] hfs: can't find a HFS filesystem on dev sda2[ 3039.949647] audit: type=1400 audit(1430243708.663:40): apparmor=STATUS operation=profile_replace name=/usr/lib/cups/backend/cups-pdf pid=5275 comm=apparmor_parser[ 3039.949668] audit: type=1400 audit(1430243708.663:41): apparmor=STATUS operation=profile_replace name=/usr/sbin/cupsd pid=5275 comm=apparmor_parser[ 3039.960604] audit: type=1400 audit(1430243708.676:42): apparmor=STATUS operation=profile_replace name=third_party pid=5275 comm=apparmor_parser[ 9265.005906] usb 1-2: new high-speed USB device number 4 using ehci-pci[ 9265.131405] usb 1-2: New USB device found, idVendor=058f, idProduct=6366[ 9265.131425] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3[ 9265.131439] usb 1-2: Product: Mass Storage Device[ 9265.131451] usb 1-2: Manufacturer: Generic[ 9265.131463] usb 1-2: SerialNumber: 058F0O1111B1[ 9265.405525] usb-storage 1-2:1.0: USB Mass Storage device detected[ 9265.405824] scsi host2: usb-storage 1-2:1.0[ 9265.406931] usbcore: registered new interface driver usb-storage[ 9265.438871] usbcore: registered new interface driver uas[ 9266.410221] scsi 2:0:0:0: Direct-Access     Multi    Flash Reader     1.00 PQ: 0 ANSI: 0[ 9266.411635] sd 2:0:0:0: Attached scsi generic sg1 type 0[ 9266.892135] sd 2:0:0:0: [sdb] 15523840 512-byte logical blocks: (7.94 GB/7.40 GiB)[ 9266.893257] sd 2:0:0:0: [sdb] Write Protect is off[ 9266.893273] sd 2:0:0:0: [sdb] Mode Sense: 03 00 00 00[ 9266.894373] sd 2:0:0:0: [sdb] No Caching mode page found[ 9266.894385] sd 2:0:0:0: [sdb] Assuming drive cache: write through[ 9266.909425]  sdb: [CUMANA/ADFS] sdb1 [ADFS] sdb1[ 9266.914006] sd 2:0:0:0: [sdb] Attached SCSI removable disk[ 9473.723355] usb 1-2: USB disconnect, device number 4[ 9478.755845] usb 1-2: new high-speed USB device number 5 using ehci-pci[ 9478.881334] usb 1-2: New USB device found, idVendor=058f, idProduct=6366[ 9478.881353] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3[ 9478.881367] usb 1-2: Product: Mass Storage Device[ 9478.881379] usb 1-2: Manufacturer: Generic[ 9478.881391] usb 1-2: SerialNumber: 058F0O1111B1[ 9478.883369] usb-storage 1-2:1.0: USB Mass Storage device detected[ 9478.883796] scsi host3: usb-storage 1-2:1.0[ 9479.886895] scsi 3:0:0:0: Direct-Access     Multi    Flash Reader     1.00 PQ: 0 ANSI: 0[ 9479.888376] sd 3:0:0:0: Attached scsi generic sg1 type 0[ 9480.368965] sd 3:0:0:0: [sdb] 15523840 512-byte logical blocks: (7.94 GB/7.40 GiB)[ 9480.370089] sd 3:0:0:0: [sdb] Write Protect is off[ 9480.370106] sd 3:0:0:0: [sdb] Mode Sense: 03 00 00 00[ 9480.371325] sd 3:0:0:0: [sdb] No Caching mode page found[ 9480.371342] sd 3:0:0:0: [sdb] Assuming drive cache: write through[ 9480.390116]  sdb: [CUMANA/ADFS] sdb1 [ADFS] sdb1[ 9480.396934] sd 3:0:0:0: [sdb] Attached SCSI removable diskHere are the partition details:    fdisk -lDisk /dev/sda: 149,1 GiB, 160041885696 bytes, 312581808 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: dosDisk identifier: 0x000b890eDevice     Boot     Start       End   Sectors   Size Id Type/dev/sda1  *         2048 308406271 308404224 147,1G 83 Linux/dev/sda2       308408318 312580095   4171778     2G  5 Extended/dev/sda5       308408320 312580095   4171776     2G 82 Linux swap / SolarisDisk /dev/sdb: 7,4 GiB, 7948206080 bytes, 15523840 sectorsUnits: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: dosDisk identifier: 0x000a4ed9Device     Boot    Start      End  Sectors   Size Id Type/dev/sdb1           8192   242187   233996 114,3M  e W95 FAT16 (LBA)/dev/sdb2         245760 15458303 15212544   7,3G 85 Linux extended/dev/sdb3       15458304 15523839    65536    32M 83 Linux/dev/sdb5         253952   376831   122880    60M  c W95 FAT32 (LBA)/dev/sdb6         385024 15458303 15073280   7,2G 83 LinuxPartition table entries are not in disk order.Gparted also says that there's a problem with superblock...Trying deroberts suggestion:mknod sdb6 b 8 22This succeeded cause there was no errorNext:e2fsck ./sdb6e2fsck 1.42.10 (18-May-2014)e2fsck: Kein passendes Gert bzw. keine passende Adresse gefunden beim Versuch, ./sdb6 zu ffnenMglicherweise ist die Partition nicht vorhanden oder eine Swap-Partition?TranslationNo fitting device or no fitting address found while trying to open ./sdb6 Maybe the partition doesn't exist or it's a swap partition?
How to repair an overclocked microsdcard?
sd card
The filesystem has gone likely read-only due to same damage, as you've guessed. fsck should fix it. Since you care about your data, and it's a relatively small device, I recommend taking a full disk image first, with something like cp /dev/sdb /root/sdcard-backup.img or pv -pterb -s 7948206080 /dev/sdb > /root/sdcard-backup.img if you have pv.When you tried to use another machine to run fsck, it failed to see the partitions. The kernel log actually leads to an explanation, though its buried and easy to miss:[ 9480.368965] sd 3:0:0:0: [sdb] 15523840 512-byte logical blocks: (7.94 GB/7.40 GiB)[ 9480.390116]  sdb: [CUMANA/ADFS] sdb1 [ADFS] sdb1[ 9480.396934] sd 3:0:0:0: [sdb] Attached SCSI removable diskI've boldfaced it there. It turns out that Linux looks for CUMANA partition tables before DOS ones and, unfortunately, a CUMANA partition table signature is one byte differentso falsely detecting one is fairly common (1256 if the data is random). There was a kernel bug filed on the false detection; the solution from the kernel folks is, basically, that partition format shouldn't generally be enabled.Your kernel, unfortunately, has CONFIG_ACORN_PARTITION_CUMANA enabled. You could switch to a different kernel that does not or recompile your kernel without that option. I've checked the Debian Jessie kernel does not enable that optionso using a Jessie kernel (one option is Debian Live), you should see the partitions and be able to fsck. Once you've done that, your Raspberry Pi should boot again. Depending on the exact corruption some files may need replacing, of course.