Yes, the bandwidth is shared between the drives. For typical HDD RAID arrays, the bandwidth is sufficient in most cases. However, if you want to operate several SATA SSDs in a RAID with a high load, the bandwidth could become a bottleneck. In such cases, a PCIe x8 or x16 card would be recommended.

The Delock SATA PCI Express x4 Card, with its PCIe 3.0 x4 lanes, provides a total bandwidth of 4 GB/s (or 32 Gb/s). Here’s how this affects the usage of multiple SATA disks:

## Bandwidth Sharing
- Since each SATA III disk has a theoretical maximum bandwidth of 6 Gb/s, connecting 16 disks would theoretically require 96 Gb/s of bandwidth.
- However, the PCIe 3.0 x4 interface of the card can only provide 32 Gb/s of bandwidth.
- This means that the disks will indeed need to share the available bandwidth, and not all of them can run at their full theoretical speed simultaneously.

## Real-Life Performance
- In real-life scenarios, the actual bandwidth usage of SATA disks is often lower than the theoretical maximum. For example, most hard drives and many SSDs do not consistently use the full 6 Gb/s bandwidth.
- For RAID arrays, while the shared bandwidth could be a limitation, it may not be as problematic if the disks are not all operating at their maximum bandwidth simultaneously. However, it is crucial to consider the actual workload and the type of disks being used.

In summary, the 32 Gb/s bandwidth provided by the PCIe 3.0 x4 interface is not sufficient to allow all 16 SATA disks to operate at their full theoretical speed at the same time, but it should be adequate for many real-world usage scenarios where disks do not constantly operate at maximum bandwidth.