Just a warning to anyone with a Promise Pegasus R6, make sure you back up to somewhere else if you are using 10.9. I just had 7TB of family photos and movies (my entire kids lives) secure in Raid 5 disappear with the update from 10.9 DP3 to DP4. The OS seems to have renamed the drive?!?! and sees it as empty. I don’t see any recovery from this. I have tried plugging the R6 into another computer and it is still seen as empty. The R6 passes all checks as running fine. Its just showing as empty. I have a backup that is only a few days old but i was VERY lucky to have it (and it is a Raid0 so i am not out of the woods yet) I know that 10.9 is in Beta, but i figured that my data was safe on an external drive if the OS died, especially in Raid5, not so obviously. Now i need something that i can back up 7TB of data to... and fast!