Normally you wouldn't but in this case you do. By default the installation will put all the storage paths on the same volume. For your case you should add a custom path for your database:
"Depending on the size of your deduplication storage, Symantec also recommends a separate path
for the deduplication database."
"CAUTION: You cannot change the paths after NetBackup configures the deduplication
storage server. Therefore, carefully decide during the planning phase where and
how you want the deduplicated backup data stored."
"The maximum deduplication storage capacity is 64 TBs. NetBackup reserves 4
percent of the storage space for the deduplication database and transaction logs.
Therefore, a storage full condition is triggered at a 96 percent threshold.
For performance optimization, Symantec recommends that you use a separate
disk, volume, partition, or spindle for the deduplication database. If you use separate
storage for the deduplication database, NetBackup still uses the 96 percent threshold
to protect the data storage from any possible overload."
If we say that you need %4 of the total for your database 64TB * %4 = 2.56TB
"64 TBs of storage:
250 MB/sec.
Symantec recommends that you store the data and the deduplication database on separate
disk, each with 250 MB/sec read or write speed."
You should overprovision that volume. It's also critical so you need a RAID array. Plus the throughput needs to be around 250MB/s. You could achieve this by striping mechanical drives with a RAID 0+1 setup or by putting some fast SSD in a RAID6. There are pros and cons to both of these setups and both are very expensive.
