FreeNAS: Open Source Storage Operating System
Storage is a really weak area of mine, but it is important, and I do not see much technical discussion here anyway, so I am going to expose myself:<p>How does integrity protection work in practice? I know that the bits on the HDD itself do not map one to one to bits you can actually use and that it uses that to protect us from flipped bits.<p>I know that beyond that RAID/RAIDZ is supposed to help. I guess redundancy alone does not help. Two copies would not help to determine which bit is the correct one, you would need three. Once you have these, I guess you would be able to detect corruption. Am I guessing correct that duplication beyond 3 times would just help with read speed and in the case when a drive fails while one is already dead (e.g. when you are rebuilding)?<p>What then? Does RAID/ZFS automatically fix it? I imagine at some point the drive would have to be replaced, do you have to check that manually or does it detect that by itself? I imagine after that you would have to run a rebuild.<p>So I guess my question would be: Could I put a FreeNas in a corner a room and leave it there? Would it just blink when I need to put a new drive in or would it need more maintenance? Of course talking about worst case scenarios here, so say I want this to live for 10 years sitting in the corner.