> From what I’ve heard, BTRFS has a crazy long list of defects where it’ll lock up or corrupt data if you so much as look at it wrong
The list cannot be crazy long if Synology uses it for their NASes.
The list cannot be crazy long if Synology uses it for their NASes.
Synology uses a hybrid BTRFS+mdadm arrangement specifically to deal with reliability problems with BTRFS RAID: https://kb.synology.com/en-us/DSM/tutorial/What_was_the_RAID...
And besides, if you are doing RAID you are probably concerned with the system's uptime which probably means you will have implemented such measures anyway.
Note that, yes, I'm aware most home users either aren't aware (nobody RTFM) or are too lazy/cheap to buy a UPS from Office Depot. So perhaps btrfs is warning people to save them from themselves.
And lost writes are a problem that all filesystems have. I recommend reading the paper "Parity Lost and Parity Regained" by Krioukov at USENIX 08...
Personally, BTRFS is the only filesystem that has ever caused me any data loss or downtime. I was using a single disk, so it should have been the perfect path. At some point the filesystem got into a state where the system would hang when mounting it read/write. I was able to boot off of a USB stick and recover my files, but I was unable to get the filesystem back into a state where it could be mounted read/write.
At work, we used to run BTRFS on our VMs as that was the default. Without fail, every VM would eventually get into a state where a regular maintenance process would completely hang the system and prevent it from doing whatever task it was supposed to be doing. Systems that wrote more to their BTRFS filesystems experienced this sooner than ones that didn't write very much, but eventually every VM succumbed to this. Eventually the server team had to rebuild every VM using ext4.
I know that anecdotes aren't data, but my experience with BTRFS will keep me from using it for anything even remotely important.
So no, I don’t think we got what we paid for.
Facebook could easily work around failures, they've surely got every part of their infrastructure easily replaceable, and probably automated at some level. I'm sure they wouldn't tolerate excessive filesystem failures, but they definitely have the ability to deal with some level of it.
But Synology deploys thousands of devices to a wide variety of consumers in a wide variety of environments. What's their secret sauce to make BTRFS reliable that my work's commercial Linux distribution doesn't have? Surely there's more to it than just running it on top of md.
Maybe in the years since I was burned by it things have greatly improved. Once bitten, twice shy though - I don't want to lose my data, so I'm going to stick to things that haven't caused me data loss.
https://kb.synology.com/tr-tr/DSM/help/ActiveBackup/activeba...