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Comment by jnxx | Hacker News Reader

Is there any technical reason why it is not supported?

Also, just for curiosity, and without condoning what the company is doing, is there a good reason to use btrfs for a device like that? I was thinking that good filesystem repair facilities are important once you store a lot of data, and btrfs is inferior to ext4 on this? I find btrfs is fantastic if you have, say, a bunch of Yocto images, or a large video you are working on, and you want to quickly create and erase snapshots of many gigabytes of data, but what is the advantage here?

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These "j" devices have like 512 MB of RAM and an ARM CPU. I believe the devices they do support BTRFS on all have 1-2 GB+ RAM and x86 CPUs.

Then how come it did work before? BTRFS as used in DSM is not particularly more memory intensive than EXT4 (which is why it did work before).

It works, but there is a risk (exacerbated if you use other features) that the device will become unstable. I believe depending on features used in btrfs it can use considerably more RAM for caching filesystem structures. While this cache can be freed, performance drops as the system need to retrieve this from the disk again. Considering reliability / reputation / performance it makes sense to not allow it as a supported configuration. However many vendors do this softly, and not as a hard lock. i.e. we won't let you create it (or we do and warn you), but if you complain / log a support ticket it will be ignored until you can show it on a supported configuration.

Synology can easily allow access to the volume. I would think the smartest decision when removing a feature (even a feature that was never intended to exist) to instead make the unit at least mount the volumes as read-only and allow the data to be exported to the network / cloud / USB drive.

I think it's RAM, not CPU. My DS418 has 2GB of RAM and an ARM CPU and supports BTRFS.

Compare that to the 4GB of a Raspberry Pi 400.

We already store a lot of data at home. And ssd and hdd storage has sometimes read errors. With terabytes of data we come across a handful error s per year, most of them will nobody notice. I use btrfs everywhere I can and see sometimes errors, most times on heavy written files like databases(sqlite files) or virtual harddisks, sometimes even pictures or logfiles. Even without RAID you could restore the file from a backup (If you try to backup a broken file, the computer won’t let you).

> Is there any technical reason why it is not supported?

No familiarity with these devices, but there is at least a slim chance if it was an embedded device, they needed the flash or RAM for something else. Seen this happen elsewhere before

Not enough RAM, possibly the CPU they chose wasn’t fully tested.

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