The future of HAMMER1

Predrag Punosevac punosevac72 at
Fri Jul 20 13:31:37 PDT 2018


I was wondering if Matt and the other developers involved can shed some
light onto the future of HAMMER1 and ultimately of DragonFly.

I started dicking with DragonFlyBSD 7-8 years ago mostly due to my
curiosity about HAMMER. I tried few times in the past to use DF as a
main file server at the place of my employment just quickly to reverse
back to ZFS and FreeBSD but my home file server is still happily running

dfly# uname -a
DragonFly 5.2-RELEASE DragonFly v5.2.2-RELEASE #17:

dfly# mount
ROOT on / (hammer, noatime, local)
devfs on /dev (devfs, nosymfollow, local)
/dev/serno/B620550018.s1a on /boot (ufs, local)
/pfs/@@-1:00001 on /var (null, local)
/pfs/@@-1:00002 on /tmp (null, local)
/pfs/@@-1:00003 on /home (null, local)
/pfs/@@-1:00004 on /usr/obj (null, local)
/pfs/@@-1:00005 on /var/crash (null, local)
/pfs/@@-1:00006 on /var/tmp (null, local)
procfs on /proc (procfs, local)
DATA on /data (hammer, read-only, noatime, local)
BACKUP on /backup (hammer, noatime, local)
/dev/serno/5QG00XF0.s1e at DATA on /test-hammer2 (hammer2, local)
/data/pfs/@@-1:00001 on /data/backups (null, local)
/data/pfs/@@-1:00002 on /data/nfs (null, NFS exported, local)

I feel the time to physically rebuild my home file server slowly
approaching so I would like to be ready for that day.

In the light of the fact that HAMMER2 is out and recommended for root
partition does HAMMER have any future? I see Tomohiro Kusumi still
having a commit or two a month which touches HAMMER but it seems that
even his commits are minor bug fixes related to his work/poking with
HAMMER2. Is everyone else done playing with HAMMER1? 

Is HAMMER2 now stable enough to guarantee consistency of my data? My
concern is that it typically takes at least 10 years for a file system
to mature under lot of use and abuse by a much wider community than DF. 
BTRFS is vaporware even after major investment since 2007. With the size
of the DF community I feel it might takes 20-30 years for HAMMER2 to be
trully safe. 

One of the main advantages for me personally of HAMMER1 over ZFS besides
fine grained history was that it seems to be ok-ish with non-ECC RAM.
Scrub of death
is real thing and I feel very uncomfortable using ZFS on my cheap home
hardware. I know that under non-budgetary constrains I should use ECC
memory with DF as well. How safe HAMMER2 is with non-ECC memory?


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