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The title says it all. Are there drawbacks in using an entire disk (/dev/sda) without any partition table for btrfs?

It seems to work, it's quite slow, though that may be because it's running on a RaspberryPi.

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up vote 3 down vote accepted

If your system can boot with a single Btrfs partition, then there is absolutely no difference whether you have a partition table or not.

In general, this depends on the system. Most bootloaders for PCs cannot load the kernel from Btrfs yet, so if / is on Btrfs, a separate /boot partition is usually needed – a partition table becomes necessary... I don't know if this applies to the boot process of Raspberry Pi, though.

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Raspberry pi can only boot off a FAT16 partition on the SD card. I imagine that if there is a disk without a partition table that it's a second drive hooked up to the USB port (on a pi, this would be /dev/sda). This could be slow for any number of reasons. Especially if it's a flash USB drive, because some are just really slow. –  Kibbee Sep 7 '12 at 19:57
But once U-Boot is loaded, there are other options if you're clever. E.G. use tftp to load the kernel, or add btrfs support and get the kernel from the disk. –  sawdust Sep 7 '12 at 22:33
I think most modern distros can boot from btrfs now. Ubuntu does give an error about sparse files but boots fine regardless (there's also a tweak to remove the error). I'm not sure about btrfs raw disk support though. –  David C. Bishop Oct 24 '12 at 11:29
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