Expand Server RAID

Hello all

I have OSX Server 10.6.8 running on an Intel Xeon Xserve.

There is a InforTrend RAID which was 3TB, and has now been expanded to 6TB. The RAID Admin software sees the new space, I have unmounted the RAID from the Xserve, rebooted both the Xserve and the RAID and still it reports 3TB.

Is there a way round this please?