Simply put, the mechanical hard drive will not be supported as a standard within Kaldus unless it is used for a media server or NAS. In which case, those drives will be 3.5″ drives, and the cost of the drives will be more expensive as they are intended for higher performance servers. For the general consumer usage – the mechanical drive is essentially dead.
To replace the mechanical hard drive, SSDs (Solid State Drives) will be the choice that is available. They are much faster, and more reliable. The price is a nominal increase due to their capability, but this will be small. SSDs come in two options. One is an Internal (SATA) option which will be in a 2.5″ form factor. The second is external (USB-C) which will plug into the computer from the outside. SSDs can range in capacities of 128GB to 8TB (8,000GB). Since mechanical drives are no longer supported for consumer use, the SSD will provide a suitable, and efficient replacement even if they are more expensive.