Please check this post - http://kb.open-e.com/System-performa...ings_1283.html

Cache setting can be changed "on-the-fly" without any risk to your data only the stripe-size change means re-RAIDing. Please get yourself a BBU for RAID card and UPS.

And remember those three simple rules of IT:

0 - do backups
1 - do backups
2 - do backups