Who installed it? An XSR should never be sold with less than a FULL compliment of drives. What are you using for your metadata controller? Where and how are you storing the metadata?
On a fully populated XSR you should be getting a conservative, reliable 300MB/s read and 200MB/s write when configured as two RAID5’s RAIDed 0, ie RAID50, direct connected.
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP