Post by @gibwar@infosec.exchange

I looked at this about a year ago and couldn't find a way to do it in BTRFS when I was setting up a new server. I ended up going with a single disk ZFS file system specifically so I could make a dataset that has copies=3 so the files would be triplicated. I went with a single disk vdev so it could detect and recover corruption while I still had an offsite backup for disaster reasons.

If you found a way to do this in BTRFS I would love to know if you're willing to share as I'd much rather use BTRFS for the server instead of ZFS for the very reasons in the thread (wider support, no custom kernel modules)

4 Replies

0 Boosts

Ken Milmore

@kbm0@mastodon.social 3 hr. ago

@gibwar @mcc @bob_zim This seems like a very odd feature to want. Having n copies of your data on *the same media* is a waste of storage space, given the known failure modes of actual media. The transition from spinning rust to SSDs has made this even more so, since you have no control over storage location. My advice: Back up your *files*. Make sure you always have three separate copies of anything important. Don't rely on snapshots or any other storage-level technology to protect your data.

Ken Milmore

@kbm0@mastodon.social 3 hr. ago

@gibwar @mcc @bob_zim Disclaimer: I do use RAID1. I wouldn't use any other RAID level. If you value your data enough, it is worth paying for at least 2x the storage. RAID5/6 are a terrible idea: Buying <=1.5x the storage is just skimping.

Zimmie

@bob_zim@infosec.exchange 2 hr. ago

@kbm0 raidz2 (RAID-6-style array for ZFS) is fine. As long as you have a gigabyte or two of RAM to throw at ARC, most workloads practically never need to read from the drives, and writes are coalesced into screaming fast sequential batches.

If you value your data, you should be using a filesystem which stores hashes for it so you know if the drives are wrong. ext4 doesn’t have an option for that. Even if it did, it isn’t aware of the other drive in a md(4) set, so it doesn’t even know there’s another copy of the data there. This is what the more advanced filesystems address.

🇺🇦 haxadecimal

@brouhaha@mastodon.social 53 min. ago

@bob_zim @kbm0
Call me paranoid, but I use raidz3 even with SSDs. I might even consider raidz4, if it existed.

1 more reply