[Bug 593086] Re: Silent wraparound on > 2 TB LVM snapshots

[Phillip Susi]

** Description changed:

  Ubuntu kernels silently wrap access to disk locations above 2 TB back
  around to zero.  This can easily be reproduced using lvm to create a
  thin provisioned virtual disk:
  
  lvcreate -s -n thin -L 1g --virtualsize 3t vg0
  
  mke2fs -t ext4 -E lazy_itable_init /dev/vg0/thin
  e2fsck -f /dev/vg0/thin
  
  Fsck will find errors in the bitmap because it is actually reading the
  superblock instead of the allocation bitmap situated just after the 2 tb
  mark.
  
+ This affects Karmic and Lucid and will cause data loss and severe
+ filesystem corruption that may go unnoticed for some time, if someone
+ creates a snapshot of a 2TB + size logical volume.  It was fixed
+ upstream as of 2.6.33.
+ 
  See comment #26 for details on the problem and what needs done to fix
  it.

-- 
Silent wraparound on > 2 TB LVM snapshots
https://bugs.launchpad.net/bugs/593086
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