The M4s are still not listed here to show the specifics of the RAID chosen for UC on UCS TRC
http://docwiki.cisco.com/wiki/UC_Virtualization_Supported_Hardware
Right now I'd assume they would be considered UC on UCS spec based, so, if you have done the necessary testing to make sure you meet the storage requirements, you'll get the support from a UC on UCS spec based.
The most common option the BU has chosen for the last TRCs is RAID 5
If you're a partner, you can post in the partner community to confirm this, otherwise, engage your SE/AM for confirmation.
According to the data sheet, your server should have plenty of RAID options
http://www.cisco.com/c/en/us/products/collateral/servers-unified-computing/ucs-c220-m4-rack-server/datasheet-c78-732386.html?mdfid=286280220
HTH
java
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