Using a truncated file for not just practice, but production?

OpenZFS
1

I’ve used truncated files plenty of times, playing with different zfs configurations, commands, etc. to practice and learn. It is a powerful playground.

Eventually, my laptop will have a proper partition for zfs, but I am not able to configure that at the moment. I’m stuck with a single ext4 partition across the whole drive.

I have a “server” at home with a pool of dedicated drives, and I also backup pool for that production pool.

I often take care of family administration tasks (paying bills, purchasing groceries, etc.) on my laptop. I maintain the permanent, root-source-of-truth copy of receipts on the server since it has a backup. But I like to keep them available locally so that I can reference them for returns, or updating my budget entries, etc.

I am not always able to connect to my server when I need access to the files, so nfs/smb doesn’t solve my problem. I have used rsync, but ensuring a file is in both locations feels like a hassle (e.g. --checksum is not default).
git would do the job simply enough, but a repo full of pdf files just for sync seems an abuse of the tool. (Maybe my proposal here is also an abuse of zfs, … partly what I’m asking.)

If I had a truncated file with a production dataset, I know zfs would inherently ensure both sides were the same via forced receive. And bonus, my e.g. paycheck stubs could be encrypted on my traveling laptop.

So my questions:

  1. is it unsafe / unwise, to use a truncated file as a production pool?
    • 1a) what {reasons | mechanisms} cause it to be a bad idea?
  2. if it were a temporary solution for only 1 small dataset (the use case above, and, I expect to be able to properly configure my laptop within 6 months), does the answer to 1) change?
  3. anything else I need to watch out for, or consider?

Thanks!

edit: minor formatting, slight sentence clarification

2

I have a cheap cloud VPS that I run some containers on. I really wanted ZFS, but the OS was pre-installed by the provider. I’ve been using ZFS on top of a file for years now to store all of my container data. Not sure I’d do it in any situation where I had any other option, but I haven’t yet seen any issues.

1 Like
3

Sweet, I’ll do it then. Thanks for the anecdotal data point! :grinning_face:
Did you use truncate to create the file, or some other method?

4

Honestly, I don’t remember. I just checked my .bash_history and it was way too long ago to still be there. My very vague recollection is that I may have used fallocate.

5

I see. I just looked up the difference between fallocate and truncate.

It made me have another question, but I think it belongs as a new topic here:

6

I can’t comment on the ZFS-specific aspects of it, but may I recommend using SyncThing to, uh, sync things? I think it might be just what you need to maintain your receipts in multiple places, with or without ZFS. It works very well in my experience.