I have a load-bearing raspberry pi on my network - it runs a DNS server, zigbee2mqtt, unifi controller, and a restic rest server. This raspberry pi, as is tradition, boots from a microSD card. As we all know, microSD cards suck a little bit and die pretty often; I've personally had this happen not all that long ago.
I'd like to keep a reasonably up-to-date hot spare ready, so when it does give up the ghost I can just swap them out and move on with my life. I can think of a few ways to accomplish this, but I'm not really sure what's the best:
- The simplest is probably cron + dd, but I'm worried about filesystem corruption from imaging a running system and could this also wear out the spare card?
- recreate partition structure, create an fstab with new UUIDs, rsync everything else. Backups are incremental and we won't get filesystem corruption, but we still aren't taking a point-in-time backup which means data files could be inconsistent with each other. (honestly unlikely with the services I'm running.)
- Migrate to BTRFS or ZFS, send/receive snapshots. This would be annoying to set up because I'd need to switch the rpi's filesystem, but once done I think this might be the best option? We get incremental updates, point-in-time backups, and even rollback on the original card if I want it.
I'm thinking out loud a little bit here, but do y'all have any thoughts? I think I'm leaning towards ZFS or BTRFS.
Which cards are you using? Just because it's samsung doesn't mean it's good.
My dashcam uses mostly this "SanDisk 256GB High Endurance Video" SD card, and my backup is a 512gb Samsung Pro Plus (not rated for dashcam use). For anything that I want reliability I use one of these SanDisk cards, that Samsung, or a SanDisk extreme that I bought the other day. My "I don't really care about this, but I'd like it to not fail" cards are Samsung Evo Select drives (or something green and Samsung). Only my "I really don't give a shit about these" drives are those $3 Microcenter cards.