Type these commands using SSH on one CVM of your cluster :

allssh ~/cluster/bin/genesis stop cluster_health
allssh ~/cluster/bin/genesis stop hyperint
allssh ~/cluster/bin/genesis stop prism
allssh ~/cluster/bin/genesis stop arithmos
allssh rm -Rf ~/data/arithmos/arithmos_per*
cluster start

Reconnect to prism and check the health status.
Note: these commands keep your cluster alive