HAMMER2 File-System Is Still Slowly Coming Together

[phoronix]

Phoronix: HAMMER2 File-System Is Still Slowly Coming Together

Back when DragonFlyBSD's HAMMER2 file-system development began being publicized, it was believed it wasn't going to be ready until at least 2013. Fast forward two years, HAMMER2 isn't yet used by default on this BSD operating system and it's still being actively developed...

http://www.phoronix.com/scan.php?page=news_item&px=DragonFly-HAMMER2-2015-1

[thesjg]

As we haven't heard much about HAMMER2 in quite some times, I was looking through the DragonFlyBSD HAMMER2 Git commits and happy to see this BTree-based file-system succeeding the original HAMMER FS is still being pursued.

HAMMER2 is Radix Tree based with indirect blocks, _NOT_ B-Tree based. The fact that HAMMER1 is B-Tree based is one of the primary reasons that its development was abandoned in favor of HAMMER2. The DragonFly development team feels that the B-Tree approach being taken by many of the rest of the filesystems under active development is the wrong direction, after nearly a decade of experience developing, modifying, and extending HAMMER1.

[gnufreex]

So what does that HAMMER2 have in comparison to BTRFS, ZFS, XFS? Can it be ported to other OSes easily? Does it work in userspace on Dragonfly? AFAIK, Dragonfly is mikrokernel, should run fs in userspace.

[TechMage89]

So what does that HAMMER2 have in comparison to BTRFS, ZFS, XFS? Can it be ported to other OSes easily? Does it work in userspace on Dragonfly? AFAIK, Dragonfly is mikrokernel, should run fs in userspace.

My understanding is that HAMMER2 is supposed to be a clustered filesystem, so it provides similar features to GlusterFS or Ceph as well as ZFS and Btrfs. It isn't as fully featured as these, but the goal of DragonflyBSD is to make clustering as easy and seamless as possible, so it's designed with that in mind.

[gnufreex]

Hm... interesting. So does it work in userspace like GlusterFS, or in kernel like CephFS?

[TechMage89]

Hm... interesting. So does it work in userspace like GlusterFS, or in kernel like CephFS?

AFAIK the stated goal of DragonflyBSD is to support clustering at a kernel level, so in kernel, I think.

[drSeehas]

... AFAIK, Dragonfly is mikrokernel, ...

No, it is hybrid kernel.

[Alex Libman]

So what does that HAMMER2 have in comparison to BTRFS, ZFS, XFS?

A genuinely free license. It's can also do with less RAM gluttony than ZFS, offer better DB performance, etc, etc, etc (see link).

Can it be ported to other OSes easily?

Good things are seldom easy...

[michael rose]

Alex Libman oko from the linked thread is clearly a great source for misinformation why would you link to that idiot?