linux - Unable to create filesystem on new partition - Amazon EC2 instance

09
2013-08
  • P K

    I created a new partition /dev/xvda1p1 on linux amazon ami. After that i am unable to create a filesystem.

    What is the issue?

    # fdisk -l

Disk /dev/xvda1: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x3ace0183

  Device Boot      Start         End      Blocks   Id  System
/dev/xvda1p1               1          14      112423+  83  Linux

# mkfs.ext4 /dev/xvda1p1
mke2fs 1.41.12 (17-May-2010)
Could not stat /dev/xvda1p1 --- No such file or directory

The device apparently does not exist; did you specify it correctly?
    • Answers
  • Vi.

    Try tricks:

    • udevadm trigger to make udev look for new devices and create /dev/xvda1p1
    • blockdev --rereadpt /dev/xvda1 to explicitly tell it to re-read partition table on it
    • mknod /dev/xvda1p1 b ${some_number} ${some_number2} manually. ${some_number} is probably the same as in /dev/xvda1 and ${some_number2} is like /dev/xvda1's, but +1.
    • Finally, you can losetup -o ${some_offset} /dev/loop0 /dev/xbda1 and use /dev/loop0. ${some_offset} is probably 8225280.

    • Related Question

    linux - How to create device driver for nested partitions?
  • NVRAM

    I'm running MSWindows virtualized with /dev/sda2 as it's primary drive. Consequently, there is a partition table on that partition, shown as:

    # fdisk -l /dev/sda2

Disk /dev/sda2: 137.4 GB, 137436203520 bytes
255 heads, 63 sectors/track, 16709 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/sda2p1   *           1       16708   134206978+   7  HPFS/NTFS

    So my question is simply: What are the major/minor numbers to create /dev/sda2p1? What about sda2p2 and sda3p1?


    • Related Answers
  • larsks

    Assuming this is a straight disk image (e.g., your virtualization solution is not adding some extra metadata to things), this document (also here) offers some suggestions for accessing your partitions on /dev/sda2 (summary: use the -o offset option to losetup to create a new block device referencing the appropriate offset into sda2).

    You can also use the Network Block Device (NBD) to create a partitioned block device from /dev/sda2, see this LWN article which described the process in detail. And hey, I just learned something new.