Comment 12 for bug 348836

I noticed some other stuff:

[ 371.568931] EXT4-fs: barriers enabled
[ 371.569257] kjournald2 starting. Commit interval 5 seconds
[ 371.569824] EXT4 FS on dm-1, internal journal on dm-1:8
[ 371.569828] EXT4-fs: delayed allocation enabled
[ 371.569831] EXT4-fs: file extents enabled
[ 371.571151] EXT4-fs: mballoc enabled
[ 371.571157] EXT4-fs: mounted filesystem with ordered data mode.
[ 379.816940] JBD: barrier-based sync failed on dm-1:8 - disabling barriers

Barriers seem to be disabled.

$ sudo lvdisplay --maps bulk/testvol
  --- Logical volume ---
  LV Name /dev/bulk/testvol
  VG Name bulk
  LV UUID q3e1GQ-zqDS-c30Z-jneb-IbEu-GijR-zOwdL5
  LV Write Access read/write
  LV Status available
  # open 0
  LV Size 125.00 GB
  Current LE 32000
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:1

  --- Segments ---
  Logical extent 0 to 31999:
    Type linear
    Physical volume /dev/sda1
    Physical extents 102333 to 134332

The volume isn't spread across both disks.

The same script running on a comparable ext3 filesystem, on the same disk, on the same machine, has had no problems.