Port 22 is used for SSH (Secure Shell), which is a secure and encrypted protocol for remote access to a server. Port 23 is used for Telnet, which is an insecure and unencrypted protocol for remote access. Port 990 is used for FTPS (File Transfer Protocol Secure), which is a secure and encrypted protocol for file transfer. The administrator should open port 22 and close port 23 to enable SSH and disable Telnet, as SSH is more secure and reliable than Telnet. The administrator does not need to open port 990, as FTPS is not required for making configuration changes.

When a drive in a RAID array is replaced, the array must rebuild the data onto the new drive. This rebuild process consumes resources and can significantly slow file access until it is complete.

RAID 5 Disk Striping with Parity
This RAID 5 design provides a good balance between performance, redundancy, and cost- effective capacity. Data is distributed across the stripes on the disks, as with RAID 0, but additional parity information is also written to the disks, which permits data to be recreated if one of the drives in the array fails. RAID 5 is a good general solution for most servers, though the performance of its writes is dependent on the RAID controller used.
RAID 5 requires a minimum of three HDDs.