@martin @daftaupe
Tried btrfs à long time ago. Snapshots Can be great for OS Drive. But for data storage nothing Can Beat mdadm+lvm2. Big problem with btrfs : you can't know how much space is still available. (At the Time i checked it at least.)

@hoper @martin You can use btrfs filesystem df for example to know how much space is available (or used). or btrfs filesystem du to get details about a particular file.

@daftaupe @martin
Seems that things change, but according to the FAQ, there are still some issues with this matter (know how much Space left and use it)
Il still think that mixing réplication (raid) and file system is a very bad idea.

@hoper @martin Well I'm using it and liking it. I never liked lvm2 and mdadm. That's the beauty of having different alternatives.


@daftaupe @martin
With how many disk ? Did you already Lost a drive or two ? WhatsApp happens then ?
Already loose 2 drives on a raid5 with mdadm and manage to get back all data. (One drive was really out of order, the other one was just suddenly disconected)

@hoper @martin Good for you but I make backups, so I'm not afraid of losing disks :D which is really easy using btrfs send/receive feature.

@daftaupe @martin
Backups are Always needed of course. But it's a "last ressort solution" because when you restore you loose data... Maybe a day of work if you backup every night. So, be able to loose disks without any impact (notre even the need to umount the filesystem) is important.

You said you have these magic send/receive #scripts, did you already #share them somewhere? Or could you #blog them maybe? 😬🙊

@martin @hoper There's nothing magical :) it's basically having 2 btrfs partitionned drives, making a snapshot of a subvolume and sending that read-only snapshot from one to the other disk. That prevent us from the use a of a tool like rsync as there's an option to send only the increment when you already have subvolumes on the other drive. Based on : btrfs.wiki.kernel.org/index.ph

@daftaupe @martin
So... Just to be sure... Sending data to another drive on the same server is what you call a "backup" ? In this case, it's not only about tools that we disagree :)

@hoper @martin I did mention another disk or drive, it's up to you to think that it's in the same server.

@hoper obviously the (incremental) snapshot should be sent to a backup-machine... 🤓
sending it to another disk in the same server sound like poor-man's raid - and as we know, #btrfs has better raid options 💾

In m'y mind, a snapshot is not a clone. It's just a sort of "diff" of two devices. Something that you can't separate from it's source.
So I dont understand how you can have a filesystem somewhere, and a snapshot of it elsewhere that can be usefull. A copy, yes. Easy. But a snapshot ? Guess there is plenty of things I dont understand about btrfs.
Maybe the first reason for me to not like it :o)

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