SQL Server disk configuration

One of our SQL servers has an interesting disk configuration. I am wondering if the community can provide me some feedback.
The server has the data broken down and placed among many different logical drives, 19 to be exact. Each drive letter is made up of a pair of 15k scsi drives mirrored using HP RAID utility. Our main database on this server has the filegroups and ndf files all on thier own hard drives, which are mirrored. The performance of the server is good. We never recieve complaints about it. The DBA who created this server left the company so I cannot ask him about it.
Can I please have any and all comments regarding this? I can add more details as necessary.

Thank You all in advance.