How to know whether disks handle flush requests correctly

[Paul Schroeder]

The btrfs wiki Main Page warns that it is currently possible to corrupt
a filesystem irrecoverably if your machine crashes or loses power on disks
that don't handle flush requests correctly.

How do you know if this applies to your drives? Is there a way to test it,
or a model list, or are newer SATA drives (magnetic, not SSDs) always ok?
Does it depend on the controller? (I have a SiI 3114, latest BIOS.)

I would also be using btrfs on top of dm-crypt (with the latest release
kernel). Some kernel versions ago, the message that write barriers aren't
supported disappeared; can I assume the device mapper / dm-crypt is not a
problem with regards to flushing?

Paul
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Converting 1-drive ext4 to 4-drive raid10 btrfs

[Paul Schroeder]

Hello!

I have a 1 TB ext4 drive that's quite full (~50 GB free space, though I
could free up another 100 GB or so if necessary) and two empty 0.5 TB
drives.

Is it possible to get another 1 TB drive and combine the four drives to
a btrfs raid10 setup without (if all goes well) losing my data?

Regards,
Paul
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