January 17, 201412 yr Hi all, as stated in a separate thread, I have a drive which was giving errors. I removed the drive from my ARRAY and started the array without the drive. My question is, what happens to the data that was on the drive which was removed, being that I did not add a drive to replace the one I removed. Will parity wait for a new drive to be added or will it try to rebuild the data from the missing drive and restore it to existing drives (there is plenty of space to do this on the remaining drives) I am getting a replacement drive later today and so wondering if the data on the missing drive needs to be copied back to the server or if unRAID will rebuild it all without my intervention. Thanks for any insight
January 17, 201412 yr UnRAID will emulate the missing drive using the other drives plus parity so data is intact. At this point you are no longer protected against another drive failing (which would lead to data loss). When you replace the failed drive unRAID will rebuild the drive and you will again be protected against a drive failure.
January 17, 201412 yr Hi all, as stated in a separate thread, I have a drive which was giving errors. I removed the drive from my ARRAY and started the array without the drive. My question is, what happens to the data that was on the drive which was removed, being that I did not add a drive to replace the one I removed. Nothing happens to it, it is being calculated from the sum of all your remaining drives to emulate the missing drive. Once you replace the drive, it will be written back to the drive, and you should do a non-correcting parity check to be sure the data that was just written can be read correctly. Ideally, you should run at least one preclear on the new drive before you put it in to ensure you didn't get a bad drive from the factory. Preclear isn't needed (or used) when replacing a failed drive, but it's still very useful to exercise the drive fully.
January 17, 201412 yr Author Is it a correct assumption to say that preclear on a 4tb drive would take 5 - 6 hours to run once?
January 17, 201412 yr Is it a correct assumption to say that preclear on a 4tb drive would take 5 - 6 hours to run once? No - it will take much longer than that! I would guess that something like 40 hours is more typical, although the exact time will depend on your hardware configuration.
January 17, 201412 yr Author Would there not be a concern of causing an issue with the drive to run a drive constantly for 40 hours, this would likely never occur in normal usage. 40 hours of writing would seem a lot of stress on any drive except ones specifically designed for running in server raid setups.
January 17, 201412 yr You are running a server, and yes, it is a lot of stress, so we want to find out whether the drive is up to the challenge BEFORE you rely on it to keep your data safe. Preclear is designed to work the drive from end to end, just like unraid will if there is a problem with another drive and it's needed to participate in the rebuild process. It will only cause an issue with the drive if it's marginal to begin with. Reading and writing is what the drive is designed to do. As long as it is kept happy with normal voltage and temperatures, it should read and write for as long as requested without errors. If it fails, we want to know sooner rather than later.
January 17, 201412 yr I ran three passes on a 3 TB drive and it took in excess of 80 hours. But, now i know the drive is solid.
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