I have a test RAID controller on my network which hosts a very large RAID 6 (11 drives, 3TB each). One of the drives failed, and the array is now rebuilding. At this rate, I think it will take about 3 days to finish. If I write new data to the array, would it decrease my chances of a successful rebuild?
I might write about 1 GB worth of new data in the form of lots of small files. Would this significantly delay the progress of the rebuild?
IO time will be consumed by the operations which will be time not available for the rebuild, slowing things down slightly, but it's definitely safe to write to the array while rebuilding.
Yes, you can write data to the array while it rebuilds. There is always an impact when writing data to the array but it shold be minor.
Writing whilst rebuilding should not decrease your chances of a succesful rebuild.
You will however notice a slight performance decrease during the rebuilding, because the controller needs some of its bandwidth to rebuild the array.