Re: [gentoo-user] btrfs only, without dracut

[Stefan G. Weichinger]

Am 17.05.2014 20:48, schrieb Greg Turner:
> On Sat, May 17, 2014 at 8:56 AM, Stefan G. Weichinger <lists@×××××.at>wrote:
>
>> It seems to not detect or interpret correctly the fact that there are 2
>> physical devices in there and then the "linux ..." line for grub.cfg
>> gets messed up, at least for me here.
>>
>
> ACK, genkernel initramfs doesn't "btrfs scan" and TSHTF.  genkernel-next
> works though.

I use dracut for generating the initramfs.

> But if you have it working now without any initramfs then
> obviously that is full of win (the LA kind, not the Redmond variety)!

I wonder if there are any real advantages of booting *with* the
initramfs even when you don't need it.

When I look at what dracut does in interaction with systemd:

https://www.kernel.org/pub/linux/utils/boot/dracut/dracut.html#dracutbootup7

https://www.kernel.org/pub/linux/utils/boot/dracut/dracut.html#_dracut_on_shutdown

... it seems to me that this adds something like an additional layer
around certain things and helps to make all that more bulletproof?

Or do I misinterpret here?

> I am a bit mystified -- or perhaps ignorant -- as to how it came to be that
> btrfs has no option to automatically initiate a scan (like md raid does,
> when it's built into the kernel as a non-module).  Surely people must want
> that feature.  I can see how scanning the wrong partitions could lead to
> terrible mayhem, though, say, in a disaster recovery scenario where you
> binary-cloned a failing drive and forgot to take the old one out before
> booting or whatever.... but btrfs has the secret sauce to most likely
> figure stuff like that out auto-magically anyhow, using the genid... so
> what gives?  Anyone know?

I don't. Not yet.