On Sun, Jul 22, 2012 at 10:55 PM, Swâmi Petaramesh <swami@xxxxxxxxxxxxxx> wrote: > You're painfully right Roman, > > A freshly formatted 1 GB BTRFS filesystem on which 81 MB of data has been > put shows only ~260 MB of free space and reserves something like 2 x 380 MB > of metadata. > > This is absolutely ridiculous of BTRFS... :-/ That's an artifact of the small size of that filesystem and the default size of allocations, which is why mixed mode exists. The metadata allocation is about 4% on most filesystems: I see 38gb of allocated but unused metadata space on a 900gb fs and 70gb on a 1.7tb fs, and the referenced threads reports 170gb on what appears to be a 4tb fs; while not ideal, it's not remotely as bad as the 25% overhead of the minimum 256mb*2 metadata allocation on a small 1gb fs*. The behaviour of a small filesystem simply isn't the same as the behaviour of a large filesystem. * Note that 1gb is still considered a very rather btrfs filesystem, for which mixed mode is recommended! -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
