We have a media-rich web application that is hosted on AWS. We have several Web Servers and we have an NFS server.
On the NFS server (Linux server) we have several EBS volumes that are mounted and we've used mdadm to implement the different mounted volumes as a single RAID volume. The Web Servers simply access the NFS storage through a mount point.
Amazon has now let us know that they will be performing power maintenance on this server in a couple of days time. Since all our media is on here it would render our site unusable for the hours while Amazon is working on it. We want to try and prevent this downtime.
I was thinking that we can prevent server downtime by perhaps setting up a new server temporarily and attaching the EBS drives (raid volume) to that server and have our web servers point there during maintenance.
This is a very high risk operation since this involves several terabytes of our production data.
What would be the safe way to move over our logical raid drive (md0) to a new amazon instance? I was hoping that I could start with building the new server, mounting the ebs volumes and assembling the RAID partition using mdadm --assemble --scan before unmounting from the existing instance so that I can first test that everything works and thus having it mounted on two instances at the same time, but I don't believe that is possible with the way that filesystems work.
How do I move a Linux software RAID to a new machine? suggests a way to move drives, but isn't really a cloud-based question. Perhaps there are simpler ways to prevent system downtime with our solution being hosted on the cloud? I have considered taking an EBS snapshot, but that tries to replicate all the many terabytes of mounted storage, so this is not a practical solution.