Chances are, that you have corrupted data stored on your server. And written to your backup. And you'll only find out, when there is no correct copy left. But help is on the way. Kind of.
Be warned: this is a rather long piece of work. I finally came around to put my diploma thesis on github, and this is a mixture of Introduction Into Memory Management, Computer Hardware, and my thesis.
The target audience for the first sections is the interested layman, later on it gets more technical. If you are really interested read the diploma thesis.
But don't worry, the post is structured and gradually gets more technical. I tried to keep technical mumbo-jumbo to the absolute minimum, and tried to explain as much, as possible.
Memory errors are bad, bad, bad. And they happen quite frequently, each year ~1/3 of Googles servers showed them. Use ECC memory in all your computers, if supported. Run a memory test program every now and then. Watch out for unexplained program crashes. Make backups.
As my diploma thesis I wrote a hybrid (kernel, userspace) memory tester for Linux that solves the main problems of current memory testprograms:
Reliably test most (~70%, YMMV) of the computers memory while still beeing able to use the computer for productive work.
If the headline made you wondering “Do I have corrupt data? Why do you think I have corrupted data?”, or if you just want to learn a bit about RAM in general, or the Linux memory management: read on.