Hi! I've read the explanation about how much space is available using disks with different sizes[1]. I understand the rules, but I see a contradiction with definition of RAID-1 in btrs:
«A form of *RAID* which stores two complete copies of each piece of data. Each copy is stored on a different *device*. btrfs requires a minimum of two devices to use RAID-1. This is the default for btrfs's *metadata* on more than one device. So, let's say we have 3 small disks: 4GB, 3G, and 2GB. If I create one file of 3GB I think that 3 GB is written on 4GB disk, it leaves 1 GB free. 3 GB of copy is written on 3 GB disk, it leaves 0 GB Free. So, I create one file of 1GB that is written on 4GB disk, it leaves 0 GB free. 1 GB of copy is written on 2 GB disk, so it leaves 1 GB free. So I've used 4GB, ok it leaves 1 GB free on only one disk, but cannot be mirrored. However as [1] I could use 4.5 ((4GB+3GB+2GB)/2) GB instead of 4GB. Surely, I'm missing or mistaking something. Please could you help me? [1]: https://btrfs.wiki.kernel.org/index.php/FAQ#How_much_space_do_I_get_with_unequal_devices_in_RAID-1_mode.3F [2]: https://btrfs.wiki.kernel.org/index.php/Glossary Thanks in advance! -- -- Sergio Belkin LPIC-2 Certified - http://www.lpi.org
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