[OpenIndiana-discuss] System disk corruption

[Robin Axelsson]

Today, I had a sudden corruption on the system disk/partition, or rather 
the zfs partition where the image file of a VirtualBox VM is located 
(i.e. not the rpool):

----------------------------------------
   pool: systempool
  state: ONLINE
status: One or more devices has experienced an error resulting in data
         corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
         entire pool from backup.
   scan: scrub repaired 0 in 0h16m with 1 errors on Sun Feb 19 10:45:28 2012
         NAME        STATE     READ WRITE CKSUM
         systempool  ONLINE       0     0     2
           c2d0p4    ONLINE       0     0     4
errors: Permanent errors have been detected in the following files:
         /systempool/images/Windows 7 x64 Ultimate.vdi
----------------------------------------

I don't understand what the "2" and "4" cksum errors mean, why the 
numbers are different and why they only lead to "1" error but I 
understand that the .vdi file is now corrupt. What is conspicuous is 
that there are _no_ errors in iostat:

----------------------------------------
c2d0             Soft Errors: 0 Hard Errors: 0 Transport Errors: 0
Media Error: 0 Device Not Ready: 0 No Device: 0 Recoverable: 0
Illegal Request: 0
----------------------------------------
So am I to understand that the cause of this is entirely software 
related? If there was an error in the hard drive then iostat should have 
returned some errors as well. This is not the first time this happens to 
me and last time it happened was on another hard drive.