[ceph-users] Ceph or Gluster for implementing big NAS

Kevin Olbrich ko at sv01.de
Mon Nov 12 06:16:55 PST 2018


Hi Dan,

ZFS without sync would be very much identical to ext2/ext4 without journals
or XFS with barriers disabled.
The ARC cache in ZFS is awesome but disbaling sync on ZFS is a very high
risk (using ext4 with kvm-mode unsafe would be similar I think).

Also, ZFS only works as expected with scheduler set to noop as it is
optimized to consume whole, non-shared devices.

Just my 2 cents ;-)

Kevin


Am Mo., 12. Nov. 2018 um 15:08 Uhr schrieb Dan van der Ster <
dan at vanderster.com>:

> We've done ZFS on RBD in a VM, exported via NFS, for a couple years.
> It's very stable and if your use-case permits you can set zfs
> sync=disabled to get very fast write performance that's tough to beat.
>
> But if you're building something new today and have *only* the NAS
> use-case then it would make better sense to try CephFS first and see
> if it works for you.
>
> -- Dan
>
> On Mon, Nov 12, 2018 at 3:01 PM Kevin Olbrich <ko at sv01.de> wrote:
> >
> > Hi!
> >
> > ZFS won't play nice on ceph. Best would be to mount CephFS directly with
> the ceph-fuse driver on the endpoint.
> > If you definitely want to put a storage gateway between the data and the
> compute nodes, then go with nfs-ganesha which can export CephFS directly
> without local ("proxy") mount.
> >
> > I had such a setup with nfs and switched to mount CephFS directly. If
> using NFS with the same data, you must make sure your HA works well to
> avoid data corruption.
> > With ceph-fuse you directly connect to the cluster, one component less
> that breaks.
> >
> > Kevin
> >
> > Am Mo., 12. Nov. 2018 um 12:44 Uhr schrieb Premysl Kouril <
> premysl.kouril at gmail.com>:
> >>
> >> Hi,
> >>
> >>
> >> We are planning to build NAS solution which will be primarily used via
> NFS and CIFS and workloads ranging from various archival application to
> more “real-time processing”. The NAS will not be used as a block storage
> for virtual machines, so the access really will always be file oriented.
> >>
> >>
> >> We are considering primarily two designs and I’d like to kindly ask for
> any thoughts, views, insights, experiences.
> >>
> >>
> >> Both designs utilize “distributed storage software at some level”. Both
> designs would be built from commodity servers and should scale as we grow.
> Both designs involve virtualization for instantiating "access virtual
> machines" which will be serving the NFS and CIFS protocol - so in this
> sense the access layer is decoupled from the data layer itself.
> >>
> >>
> >> First design is based on a distributed filesystem like Gluster or
> CephFS. We would deploy this software on those commodity servers and mount
> the resultant filesystem on the “access virtual machines” and they would be
> serving the mounted filesystem via NFS/CIFS.
> >>
> >>
> >> Second design is based on distributed block storage using CEPH. So we
> would build distributed block storage on those commodity servers, and then,
> via virtualization (like OpenStack Cinder) we would allocate the block
> storage into the access VM. Inside the access VM we would deploy ZFS which
> would aggregate block storage into a single filesystem. And this filesystem
> would be served via NFS/CIFS from the very same VM.
> >>
> >>
> >> Any advices and insights highly appreciated
> >>
> >>
> >> Cheers,
> >>
> >> Prema
> >>
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> >
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