I have a 2 bay NAS, and I was planning on using 2x 18tb HDDs in raid 1. I was planning on purchasing 3 of these drives so when one fails I have the replacement. (I am aware that you should purchase at different times to reduce risk of them all failing at the same time)
Then I setup restic.
It makes backups so easy that I am wondering if I should even bother with raid.
Currently I have ~1TB of backups, and with restics snapshots, it wonβt grow to be that big anyways.
Either way, I will be storing the backups in aws S3. So is it still worth it to use raid? (I also will be storing backups at my parents)
Yes, I would still do raid. Because a disk fail will not cause a blackout. Much better than have your server offline waiting to replace disk and restore backup.
And no way you can backup 18tb in 1tb, restic or no restic.
RAID is 100% about uptime, not backups. If you want less downtime then RAID is your friend.
Having said that, RAID in modern systems is broken and you should use ZFS instead: https://www.youtube.com/watch?v=l55GfAwa8RI
RAID means that if a drive fails you donβt have some downtime while your backups restore. It depends on how you feel about waiting for that.
RAID 1 is mirroring. If you accidentally delete a file, or it becomes corrupt (for reasons other than drive failure), RAID 1 will faithfully replicate that delete/corruption to both drives. RAID 1 only protects you from drive failure.
Implement backups before RAID. If you have an extra drive, use it for backups first.
There is only one case when itβs smart to use RAID on a machine with no backups, and thatβs RAID 0 on a read-only server where the data is being replicated in from somewhere else. All other RAID levels only protect against drive failure, and not against the far more common causes of data loss: user- or application-caused data corruption.
I know itβs not totally relevant but I once convinced a company to run their log aggregators with 75 servers and 15 disks in raid0 each.
We relied on the app layer to make sure there was at least 3 copies of the data and if a nodeβs array shat the bed the rest of the cluster would heal and replicate what was lost. Once the DC people swapped the disk we had automation to rebuild the disks and add the host back into the cluster.
It was glorious - 75 servers each splitting the read/write operations 1/75th and then each server splitting that further between 15 disks. Each query had the potential to have ~1100 disks respond in concert, each with a tiny slice of the data you asked for. It was SO fast.
Raid 1 has saved my server a couple of times over from disaster. I make weekly cold backups, but I didnβt have to worry about it when my alert came in notifying me which drive went dead - just swap, rebuild, move along. So yeah Iβd say itβs definitely worth it. Just donβt treat raid as a backup solution - and yes, continue to use an external cold storage backup solution as you mentioned. Fires, exploding power supplies, ransomware, etc donβt care if youβre using raid or not.
