how to do if the shared storage disappear in VCS

Hello,

   i use VCS to cluster server connected to san with 2 san switch (reduncant to gether) . soon i have to power off one san switch, for  worse case, the questions are

-  do i have to stop clustering or unmount shared disk to do so?

-  how to do if the san switch redundancy fail (making san storage is disappear from server)?

thank you

tep