Petar Bogdanovic writes:
> Hi,
> 
> raidctl(8) says:
> 
> 	``-i (...) MUST be done for all RAID sets before the RAID device
> 	     is labeled and before file systems are created on the RAID
> 	     device.''
> 
> I usually don't question sentences which begin with a uppercase must but
> since I forgot to initialize my raid0 before doing all the labels and
> file-systems it makes me wonder why my system works, resp. why it could
> fail without a prior initialization.

If the parity on the RAID set is not in sync and a component dies, 
then data will likely be lost (and/or filesystems corrupted, panics, 
etc.)  If you can live with that risk, then you are free to 
initialize the parity when you please.  To be safe in the general 
case, however, you will want to initialize the parity *before* using 
the RAID set.  The "MUST" is there to encourage the initialization of 
parity early on.  It is there especially for those folks who do not 
know (or don't wish to know) the implications of not doing the parity 
initialization before trusting data to the set...

Later...

Greg Oster