Everybody gets spikes, but that pattern where they show up at regular, predictable intervals is uncommon.
I don’t see that pattern on my setup, but I have seen a lot of scans that do show it in this forum and at AtomicPC. There has been a fair amount of speculation on what causes them.
Nobody seems to know for sure, but it seems to be hardware specific. Some have suggested unstable power supplies, bad IDE cables, funky chipset issues, too much grease on the rods in the drive itself, etc.
The only thing that people seem to agree on is that some users see spikes and others don’t. The one that do can’t seem to get rid of them, though some combinations of firmware and media make them less obvious.
Another open question is whether they really hurt anything. You max PI is quite good, spikes or not, and the PO is fine except for two random spikes that shouldn’t be cause for concern.
Like a lot of other Kprobe anomalies, my advice is if they play OK, “Don’t worry, be happy.”