Synology's DS1819+ can have up to 18 storage bays, more - 9to5Toys
DS1819+ upgrade – NAS Compares
Synology DS1819+ NAS Review
Amazon.com: Synology DiskStation DS1819+ iSCSI NAS Server with Intel Atom 2.1GHz CPU, 16GB Memory, 32TB HDD Storage, DSM Operating System : Electronics
Amazon.com: Synology DiskStation DS1819+ iSCSI NAS Server with Intel Atom 2.1GHz CPU, 16GB Memory, 8TB SSD Storage, DSM Operating System : Electronics
Synology DS1819+ Review - StorageReview.com
Amazon.com: Synology 8 Bay NAS Diskstation (Diskless) (DS1819+) : Electronics