title: Attaching and mounting existing EBS volume to EC2 instance filesystem issue
body: <p>I had some unknown issue with my old EC2 instance so that I can't ssh into it anymore. Therefore I'm attempting to create a new EBS volume from a snapshot of the old volume and mount it into the new instance. Here is exactly what I did:</p>
  
  <ol>
  <li>Created a new volume from snapshot of the old one.</li>
  <li>Created a new EC2 instance and attached the volume to it as <code>/dev/xvdf</code> (or <code>/dev/sdf</code>)</li>
  <li><p>SSHed into the instance and attempted to mount the old volume with: </p>
  
  <p><code>$ sudo mkdir -m 000 /vol
  $ sudo mount /dev/xvdf /vol</code></p></li>
  </ol>
  
  <p>And the output was:</p>
  
  <pre><code>mount: block device /dev/xvdf is write-protected, mounting read-only
  mount: you must specify the filesystem type
  </code></pre>
  
  <p>I know I should specify the filesytem as <code>ext4</code> but the volume contains a lot of important data, so I cannot afford to format it with <code>$ sudo mkfs -t ext4 /dev/xvdf</code>. If I try <code>sudo mount /dev/xvdf /vol -t ext4</code> (no formatting) I get:</p>
  
  <pre><code>mount: wrong fs type, bad option, bad superblock on /dev/xvdf,
         missing codepage or helper program, or other error
         In some cases useful info is found in syslog - try
         dmesg | tail  or so
  </code></pre>
  
  <p>And <code>dmesg | tail</code> gives me:</p>
  
  <pre><code>[ 1433.217915] EXT4-fs (xvdf): VFS: Can't find ext4 filesystem
  [ 1433.222107] FAT-fs (xvdf): bogus number of reserved sectors
  [ 1433.226127] FAT-fs (xvdf): Can't find a valid FAT filesystem
  [ 1433.260752] EXT4-fs (xvdf): VFS: Can't find ext4 filesystem
  [ 1433.265563] EXT4-fs (xvdf): VFS: Can't find ext4 filesystem
  [ 1433.270477] EXT4-fs (xvdf): VFS: Can't find ext4 filesystem
  [ 1433.274549] FAT-fs (xvdf): bogus number of reserved sectors
  [ 1433.277632] FAT-fs (xvdf): Can't find a valid FAT filesystem
  [ 1433.306549] ISOFS: Unable to identify CD-ROM format.
  [ 2373.694570] EXT4-fs (xvdf): VFS: Can't find ext4 filesystem
  </code></pre>
  
  <p>By the way, the 'mounting read-only' message also worries me but I haven't look into it yet since I can't mount the volume at all.</p>
  
  <p>Thanks in advance!</p>