In a week of stumbling around I managed to mount 4x 2TB Seagate Barracuda drives into a software RAID10 array and filled them up with music, movies and all my family’s documents and photos.
I looked upon my work and saw that it was good.
Between the 7th and 1168th day I rested, safe in the knowledge that a RAID array is the best possible backup system for one’s data. On the 1169th day I tried to log in to the server remotely and update it (as I do roughly every 3 months). No response.
I couldn’t tell the server’s status, but it was still powered on, meaning that (depending when the first disk died) there could have been up to 12 weeks of the array sitting there in a degraded state, not good because degraded arrays make the other drives more likely to fail. MDADM’s warning emails had failed to trigger and the reality came crashing down: Putting your data in a RAID array isn’t backing it up, it just allows you to keep going with minimum downtime in the event of hardware failure.
Years’ worth of documents and family photos (stored in no other location because “the RAID is the backup! Durrrr!”) now hung in the balance, but fortunately, only one disk had failed and somehow (Odin be praised) the server had reset and couldn’t get past boot without some user input. It didn’t try to remount the array and the other disks survived.
With some help from a friend, I managed to remount the degraded array and copy all the data safely onto a brand new NAS box (yes with real RAID friendly drives in it this time). I’m setting up the online backup as we speak.
Had I thought this through when I built the damn thing I no doubt would have organized some sort of actual backup to an online service, I was just saved by a lucky chain of events.
But you might not be so lucky! So for critical data, remember to treat the RAID arrays in your servers or NAS boxes as ‘uptime contingencies’ and make separate backups!
TLDR: Back your data up bro.