Should I use RAID5/6 or 10 on an N5200 Pro?

[FatalSaviour]

I'm just about to buy another NAS, for yet another office that work would like be to set up. I've decided to go for the Pro version this time, as its iSCSI functionality will be used with an SBS 2008 Server for backups etc.

In the past, I've put either a RAID 5 or 6 array in place. However, I was thinking whether it might be better to start using RAID 10?

Is RAID 10 only able to withstand one drive failure, if a 2nd drive in the same mirror were to fail?
What are the performance differences like between the various RAID levels?

Thanks for your input everyone

[msx8280]

Under Raid 10 you may survive with 2 disc failures, assuming that these two drives are from the diffeirent mirror.

Under Raid6 you will make it with 2 drive failures, no matter which one is it