Hey Craig, welcome to the world of server hardware—great question, and totally understandable to feel unsure when you're just starting out!

First off, the model you're eyeing (HP ProLiant DL380 Gen9, which matches those E5-2640v4 CPUs you mentioned) comes with backplanes that support both SAS and SATA drives right out of the box for most standard configurations.

Let me break this down simply: Most DL380 Gen9 units use a universal backplane built to work with both drive types. The key thing to note is your storage controller—if it's a typical Smart Array controller (like the P440ar, which is super common for this model), it natively supports both SAS and SATA drives (though for the best performance, it’s a good idea to stick to one drive type per logical array).

You mentioned checking HP support docs, and that’s a solid move. Those official specs do confirm the server’s backplane is compatible with both 2.5" and 3.5" SAS/SATA drives, depending on your specific backplane size. You won’t need to swap out the backplane unless you’ve got an extremely specialized, older configuration that was built exclusively for one drive type—and that’s pretty rare for Gen9 models.

As for comparing to Lenovo servers: Universal backplane support for both SAS and SATA is a standard feature across enterprise-grade servers from major vendors like HP, Lenovo, and Dell these days. So you don’t have to stress about being locked into only SAS drives here.

A quick pro tip to be 100% certain: Boot into the server’s iLO (Integrated Lights-Out) interface—it’ll show you detailed hardware specs, including your backplane’s exact capabilities. If you don’t have iLO access yet, you can also look for the part number sticker on the backplane itself and cross-reference it with HP’s part listings to confirm compatibility.

备注：内容来源于stack exchange，提问作者Craig