RAID 5 needs one spare, so you'd need nine drives.

That said, 4T support is limited in systems (many of recent vintage) and may run into operating system problems as well.

Yeah, strictly speaking, you need 9x4TB in RAID 5 to hit 32GB, but I wouldn't do it.  If you "must" have a single 32TB volume, use 10 drives in a RAID 6.  It will take DAYS (possibly a week or more, depending on the drive types, controller, load, etc.) to rebuild a drive that fails or simply goes offline.  That is DAYS that your data is susceptible to an almost-guaranteed amount of data loss.  RAID 6 will protect the integrity of the array while a single disk is offline and/or rebuilding.

What controller are you using for this amount of data?
What drives (make/model) do you plan to use?
What system (this obviously won't be a desktop project)?
What kind of data will you be storing?

Second, for using raid 6. With 32TB your just asking for a failure with raid 5. If possible, you would be better off with 2 smaller raid 6 arrays, but would require a large number of available slots. Why is a 32TB array required... curious?

Thanks for the information. We are planning to use Powervault NX3200 for video storage. Please confirm that i need only 9 x 4TB physical HDD to have 32GB RAID 5 configuration? Is that correct? 

Thanks for the reply. We will use it for Network Video Recorder storage.

Thanks. So you mean i need only physical 9 x 4TB HDD to have 32 GB Raid 5 Storage configuration for Powervault NX3200?

Yes, RAID 5 uses one disk's worth of space for parity, spread out across the entire set of disks, regardless of how many disks there are.  So, if you want RAID 5, you need one extra disk. 

Just remember that if a drive ever dies, in the length of time it takes a 4TB disk to rebuild, your data integrity is at risk, as you are almost guaranteed an unrecoverable read error with nothing to protect you against it (meaning you have lost or corrupted data).

Thanks vry much for the information.