Yes, you can use a SATA hard drive in an older HP Proliant DL380 G6 server, but there are a few things to bear in mind. The DL380 G6 uses SAS (Serial Attached SCSI) hard drives for its internal storage system. However, it is also possible to use SATA hard drives with certain limitations.

The DL380 G6 has internal SAS drive bays that support 2.5-inch SAS drives. If you wish to use a SATA hard drive in this server, you will need a SAS to SATA adapter to connect the SATA hard drive to a SAS disk bay. This can be purchased from third party suppliers or direct from HP if available.

However, it is important to note that using a SATA hard drive with an adapter may result in lower performance than using a native SAS hard drive. SAS hard drives are generally designed to provide superior performance and reliability in an enterprise environment.

It is recommended that you consult the HP Proliant DL380 G6 server's specific user guide or technical documentation for detailed information on hard drive compatibility and manufacturer recommendations.

This should work because the HP ProLiant DL380 G6 uses SAS disks, but the connector in the hotplug case can also handle SATA disks, but you cannot mix SAS and SATA disks in the same backplane, i.e. a possibly existing SAS disk would also have to be removed. It is also possible to build an array with SATA disks, e.g. if you want to use several disks of the same interface type. The RAID controller in the DL380 G6 is not so picky.