In short: 3-2-1 backup strategy + Disaster recovery plan.
## Backup strategy
You should have:
- 3 copies of data
- on 2 different types of storages
- including 1 off-site copy
AND you must test disaster recovery plan
### Why so many copies?
What if you accidently delete important files that you frequently edit? That's the reason to have snapshots.
What if your main drive with data will die? That's the reason to have backup nearby.
You think that you smart and have RAID for all those cases? Did you know that in drive arrays, one drive's failure significantly increases the short-term risk of a second drive failing. That's the reason to have off-site backup.
What if your main storage Server will die with all drives in it due to power spike (flood,etc...)? So, do off-site backups.
Proxmoxx Backup Server at another city (e.g. at friend's house) with RAID1/5/6
(thou you should set it up so if malware/hacker would get to root user it won't overwrite backups)
#### Pros
- Ideal if you already have homeserver and want to expand
- Low chances of loosing data because you essentially have 3 copies (by default, 2 min) of data + hourly/daily/weekly/montly snapshots
So if you get 2 dead drives in a same time - you still won't loose your data
Essentially it covers 2 copies of data
- If drive fails - you simple take it out, put new drive in and say that you want add this drive to pool via WebGUI
- With SSD cache you can throw in any trashy HDD drives until they start to fail
- You can add any number of drives
- And if you need/want to be able to freely shutdown one of a servers and still be able to access data - you need to distribute drives so their raw storage would be even on each server.
Or just add in few more server and distribute drives between them so you would still be able to access this storage
- If you get your house+servers destroed - you wouldn't loose your data
- You can access your storage from any device in your network as if it is on it device
#### Cons
- Expect 30% usable space from raw storage (you can use Erasure Coding (RAID5 analog) but it will be even slower)
- Bad/Slow (in terms of IOPS and delay times) drives without PLP SSD cache can have amazingly bad total speed
- Power usage might be a burden if you don't have any
- More performance comes with more drives because speed = available IOPS and avarage access time for 2-3 drives that have that data. So more drives, more IOPS we have (excluding SSD cache case)
- Ceph can be complicated to understand and maintain in case of failures
### Home-server (Medium cost, medium difficulty, hard to maintain)
CIFS/WebDAV/Nextcloud Share:
- get any PC, install linux on it, setup Samba/WebDAV/Nextcloud share
- X number of drives in RAIDZ (4+ even drives) (ideally RAIDZ2)