[Bug 802081] Re: qemu raw/nocache fails to operate on LVM partition with 4k sector size

[cyberconte]

** Description changed:

  On the host machine, a disk is configured with 4k sector sizes:
  ---
  sudo fdisk /dev/sdd
  
  Disk /dev/sdd: 4000.6 GB, 4000627818496 bytes
  255 heads, 63 sectors/track, 60797 cylinders
  Units = cylinders of 16065 * 4096 = 65802240 bytes
  Sector size (logical/physical): 4096 bytes / 4096 bytes
  I/O size (minimum/optimal): 4096 bytes / 4096 bytes
  Disk identifier: 0xf8eabb69
  ---
  ... and when fdisking the lvm parition, also reports properly:
  ---
  Disk /dev/VMsVG/mail: 21.0 GB, 20971520000 bytes
  255 heads, 63 sectors/track, 318 cylinders
  Units = cylinders of 16065 * 4096 = 65802240 bytes
  Sector size (logical/physical): 4096 bytes / 4096 bytes
  I/O size (minimum/optimal): 4096 bytes / 4096 bytes
  Disk identifier: 0x6a3bdb21
  ---
- However, within a VM using the LVM parition as a raw disk, its fdisk reports a 512 block size:
+ However, within a guest VM using the LVM parition as a raw disk, its fdisk reports a 512 block size:
  ---
  Disk /dev/vda: 21.0 GB, 20971520000 bytes
  16 heads, 63 sectors/track, 5079 cylinders
  Units = cylinders of 1008 * 4096 = 4128768 bytes
  Sector size (logical/physical): 4096 bytes / 4096 bytes
  I/O size (minimum/optimal): 512 bytes / 512 bytes
  Disk identifier: 0x915c306a
  
  using cache=none, which is established practice for best performance on
- raw devices, the host system repeatedly fails to write to the disk, due
+ raw devices, the guest system repeatedly fails to write to the disk, due
  to it trying to write 512 byte sectors while the backing is 4096.
+ 
+ Both systems are using Ubuntu 11.04 server.

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https://bugs.launchpad.net/bugs/802081

Title:
  qemu raw/nocache fails to operate on LVM partition with 4k sector size

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