DragonFlyBSD下个发行版将会有Hammer2文件系统

[acheng]

Dfly BSD的创始人Matthew Dillon宣布，下个发行版中将会带有（实验性的）Hammer2文件系统。

The next DragonFly release (probably in September some time) will have an
initial HAMMER2 implementation. It WILL be considered experimental and
won't be an installer option yet. This initial release will only have
single-image support operational plus basic features. It will have live
dedup (for cp's), compression, fast recovery, snapshot, and boot support
out of the gate.

This first H2 release will not have clustering or multi-volume support, so
don't expect those features to work. I may be able to get bulk dedup and
basic mirroring operational by release time, but it won't be very
efficient. Also, right now, sync operations are fairly expensive and will
stall modifying operations to some degree during the flush, and there is no
reblocking (yet). The allocator has a 16KB granularity (on HAMMER1 it was
2MB), so for testing purposes it will still work fairly well even without
reblocking.

The design is in a good place. I'm quite happy with how the physical
layout turned out. Allocations down to 1KB are supported. The freemap has
a 16KB granularity with a linear counter (one counter per 512KB) for
packing smaller allocations. INodes are 1KB and can directly embed 512
bytes of file data for files <= 512 bytes, or have four top-level blockrefs
for files > 512 bytes. The freemap is also zoned by type for I/O locality.

...

http://lists.dragonflybsd.org/pipermail ... 13558.html