Jtdylktuy

I am rebuilding a home server after my previous one failed (My Odroid C1 with 1GB RAM running Ubuntu 14.04 was just struggling with RAM and other things that made it hang; my mdadm-lvm RAID1 storage system failed entirely, both disks ended up with tons of bad blocks, maybe partly because of the initial system being in a bad state, and I've had a bad experience trying to recover any of the data ...).

I now have a UDOO x86 with 4GB RAM and Ubuntu 18.04 taking care of:

• a web server (nginx + mysql)


• a mail server (dovecot + postfix)


• Nextcloud and its different apps (file storage/sharing, cardDAV, calDAV, IMAP client)

This is to say that it's for simple "family" use, I am not expecting tons of traffic unless I suddenly become famous. Everything works like a charm, except that my eMMC is limited to 32GB and I need storage space. My wishes are:

• Backup
  
  
  
  
  1. Data must be stored in places I physically control
  
  
  2. Simple to setup from multiple local sources (eMMC + storage of my server, but also ability to backup my laptop) to the same target(s)
  
  
  3. Easy to restore file from a backup (if my storage system completely fails/burns/is stolen).
  
  
  
  


• Storage
  
  
  
  
  4. 2TB storage space, to store dovecot mail folders, nextcloud storage files, other ad-hoc storage (e.g. pictures), and some website files
  
  
  5. If possible: ability to minimise the risk of backing up errors, and minimise the need to restore from backup when things go wrong
  
  
  6. Low maintenance and flexibility to the extent possible
  
  
  
  


• Over consideration over my data: I don’t hold strategic data, maybe pictures and documents that I would to keep for the long term as optimally as possible. I would be pissed if I need to restore from the latest monthly, but as long as it’s easy I wouldn’t be totally devastated to have to rewrite my latest article or lost the pictures from my last trip. Of course if this can be easily avoided I’d be more than happy to consider that option. However backed up data need to be errorless.

Reading around dozens of blog or forum posts, I understood that backup is the most important thing. Ideally backup should be done to another machine (to avoid cascading risks being linked to the system we want to backup), at another physical address (to cope with risk of fire, theft, ...), and ideally at multiple locations. I will take the risk to store things just on another drive, and it sounded good to me using restic scheduled with systemd. Please raise a red flag if you think there's much better, otherwise we can move on.

For the storage part, I have to admit I was quite confused by the range of forum and blog posts I've read, which covered a wide range:

• Some argue that the most important is backup, and you can just have your system designed to fail. (needs 1 drive with ext4)


• Others encourage merging multiple drives but with non real-time snapshots: JBOD (MergerFS) + snapRAID (needs at least 2 drives)


• The rest seem to agree that the best filesystem is ZFS, although it uses a lot of RAM, is rigid (same disk volume) and it’s expensive to expand (needs: Mirror >= 2 drives RAIDZ >= 3 drives RAIDZ2 >= 4 drives)


• Is it still worth considering Linux software RAID with mdadm + lvm? I've had a bad experience with RAID1...

Given all the above, what would be your recommendation?

K.I.S.S. No need to complicate things if there is not a good reason to do so.

1. RAID is not a backup system, it doesn't protect you against accidental deletion/alteration.




2. A problem with "snapshots" is that they aren't selective and it is not always easy to recover just a handful of files from them.




3. If you have a low update rate, a cloud backup could be OK. Usually writing is cheap, reading is expensive, so this is a good solution if you think you'll only have to occasionally restore a couple of files but restoring the whole 2TB is going to be expensive (and slow).




4. A local disk is a good first step, but if there is a fire/burglar you can lose everything. What you can do is have two backup disks, and swap them regularly, keeping the second disk elsewhere (office/parent/sibling/friend).




5. A hybrid solution with a monthly backup to local disk (kept outside the house) and frequent backups to the cloud make restoring the system faster, and less expensive, since you can restore most of it from the monthly backup.

PS: I'm not sure the eMMC is designed to support the update rate of a live Linux system.