I think i am facing similar kind of issue where sometimes dd works and
sometimes it say read only file system, but not able to alter the partitions on
flash drive.
df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/sdb1 vfat 3.8G 2.5G 1.4G 65%
/media/tushar/TRANSCEND1
Zeroing out whole disk does not report any I/O issue.
tushar@tushar-Studio-1555:~$ sudo dd if=/dev/zero of=/dev/sdb1 bs=1M count=4096
dd: error writing ‘/dev/sdb1’: No space left on device
3829+0 records in
3828+0 records out
4014866432 bytes (4.0 GB) copied, 227.406 s, 17.7 MB/s
Specific region doesn't report any issue in dd.
tushar@tushar-Studio-1555:~$ sudo dd if=/dev/zero of=/dev/sdb seek=446 bs=1
count=64
64+0 records in
64+0 records out
64 bytes (64 B) copied, 0.000310444 s, 206 kB/s
removing MBR
tushar@tushar-Studio-1555:~$ sudo dd if=/dev/zero of=/dev/sdb seek=512 bs=1
count=64
64+0 records in
64+0 records out
64 bytes (64 B) copied, 0.000279994 s, 229 kB/s
when i manually mount dd responds as below.
sudo mount | grep sdb
tushar@tushar-Studio-1555:~$ sudo mount -o rw -force /dev/sdb
/media/tushar/TRANSCEND
tushar@tushar-Studio-1555:~$ sudo mount | grep sdb
/dev/sdb on /media/tushar/TRANSCEND type none (rw,rce)
tushar@tushar-Studio-1555:~$ sudo dd if=/dev/zero of=/dev/sdb seek=446 bs=1
count=64
dd: failed to open ‘/dev/sdb’: Read-only file system
tried to repartition on the disk but writing is failing.
sudo fdisk -l /dev/sdb
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 256 7841791 3920768 b W95 FAT32
tushar@tushar-Studio-1555:~$
tushar@tushar-Studio-1555:~$ sudo fdisk /dev/sdb
Command (m for help): p
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 256 7841791 3920768 b W95 FAT32
Command (m for help): d
Selected partition 1
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Error closing file
tushar@tushar-Studio-1555:~$ sudo fdisk /dev/sdb
You will not be able to write the partition table.
Command (m for help): p
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 256 7841791 3920768 b W95 FAT32
Command (m for help): d
Selected partition 1
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
Using default value 1
First sector (2048-7841791, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-7841791, default 7841791):
Using default value 7841791
Command (m for help): p
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 2048 7841791 3919872 83 Linux
Command (m for help): w
fdisk: unable to write /dev/sdb: Bad file descriptor
tushar@tushar-Studio-1555:~$ sudo fdisk /dev/sdb
You will not be able to write the partition table.
Command (m for help): p
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 256 7841791 3920768 b W95 FAT32
Command (m for help): q
=======================================================================================
=======================================================================================
tushar@tushar-Studio-1555:~$ sudo fdisk -l /dev/sdb
Disk /dev/sdb: 4014 MB, 4014997504 bytes
57 heads, 56 sectors/track, 2456 cylinders, total 7841792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 256 7841791 3920768 b W95 FAT32
tushar@tushar-Studio-1555:~$ sudo parted -l /dev/sdb
Model: ATA WDC WD10JPVT-00A (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Number Start End Size Type File system Flags
1 1049kB 800GB 800GB primary ext4 boot
2 800GB 1000GB 200GB extended
5 800GB 801GB 999MB logical
6 801GB 1000GB 199GB logical ext4
Warning: Unable to open /dev/sdb read-write (Read-only file system). /dev/sdb
has been opened read-only.
Model: JetFlash Transcend 4GB (scsi)
Disk /dev/sdb: 4015MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 131kB 4015MB 4015MB primary fat32
Model: Linux device-mapper (crypt) (dm)
Disk /dev/mapper/cryptswap1: 999MB
Sector size (logical/physical): 512B/4096B
Partition Table: loop
Number Start End Size File system Flags
1 0.00B 999MB 999MB linux-swap(v1)
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https://bugs.launchpad.net/bugs/58331
Title:
fdisk doesn't write partition table
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