vmax40k; how many Drive Bay SPS failures can system tolerate

We have now ageing vmax40k where disks and SPSs regularly fail.

Note that a drive bay has 8 SPS units ...how many failures can the Bay tolerate ...and what happens if any limit is  breached ?

We have one  failure presently ..what is impact of a second, or  third failure.?

Is it limited to vaulting ability on that bay (hence entire array) but will not prevent unit from serving data , albeit with multiple SPS failures ?

Thoughts appreciated !

Thanks , john