So, I bought 500GB ST500DM009 Seagate Barracuda few days ago and I'm still checking it before the "guaranteed return policy" from the said online shop expires. Everything seems okay, except one thing: the cache buffer size is not shown anywhere in HDD checker tool. I checked with CrystalDisk Info, HDTune, and HDD Sentinel, and none of them shows the amount of the buffer size. I asked ChatGPT while waiting the search result for the problem. The ChatGPT said it might have firmware problems, while the search result said "The maximum value that could ever be stored in word 21 is FFFFh. A modern disk drive with 32 MB of buffer would need one more byte to represent the buffer size: 10000h. The first two bytes of 10000h (word 21) is 0000h, or zero.". So which one is right? I don't have other HDD that has 32MB of cache buffer so I can't compare and draw conclusions about it. The disk specification from Seagate: (link here, page 9)
HDD information checked with various HDD checking tool: