They have bigger disk options.  I found the answer now anyway, its about 19TB RAID50 with 24 x 1.2TB disks. Thanks.
Hi  Im just wondering what the usable capacity is on the PS6210X is when using 24 x 1.2TB with RAID50?   The older PS6110X we have gives 14.14TB using RAID50.   Cheers
Usable capacity question on PS6210X