Re: [vserver] btrfs/hashify/cow....

From: John A. Sullivan III <>
Date: Mon 10 Sep 2012 - 01:42:24 BST
Message-ID: <>

On Sun, 2012-09-09 at 10:21 +0100, Gordan Bobic wrote:
> >> I never tried it, so I cannot comment either way. After the BTRFS devs
> >> didn't manage to understand why CoW hard-links would be useful as a FS
> >> feature (without vserver), and after some of the comments they made
> >> regarding deduplication features and how (and whether) they plan to
> >> implement it in BTRFS, I made a firm decision I'm not going to touch it
> >> with a barge-pole. Ever. If these are the people designing and
> >> developing the FS, I'm not prepared to entrust my data to it. Where my
> >> requirements are feature-rich, I have switched to ZFS (ZFS-on-Linux
> >> kernel driver, not the fuse implementation) and never looked back. I
> >> still think it was the right decision.
> >
> > We've been using ZFS on OpenSolaris as I've heard the BSD implementation
> > is poor and the FUSE implementation does not perform as well. I was not
> > aware there was a ZFS-on-Linux kernel driver. I was under the
> > assumption the licenses were incompatible and hence FUSE was the only
> > Linux option.
> I haven't tried it, but from everything I've heard the BSD ZFS
> implementation is _awesome_. It even has some features that the
> OpenSolaris implementation lacks (e.g. TRIM/discard). FUSE
> implementation is handy as a fallback option if you have a problem (make
> sure you create a pool with version that can be accessed by all the
> implementations you might want to try it on).
> As for licencng - yes, the ZFS licence means it cannot be shipped with
> the mainline kernel, but there's nothing at all stopping it from being
> shipped as an external module.
> And BSD people have a much more healthily pragmatic view of licencing
> nit-picking in this sense, as is evident from the fact that they've had
> ZFS support in their kernel for years.
> > Is this real ZFS on Linux?
> Yes. (As opposed to what? Fake ZFS on Linux?)
As opposed to running it as a FUSE file system.
> > Does it compare in features and performance to OpenSolaris?
> Yes.
> > If so, I think it would be even better than OpenSolaris
> > as it appears the network stack latency is lower in Linux than
> > OpenSolaris from what we've seen. Thanks - John
> ZFS doesn't go anywhere near the network stack so I don't know what
> exactly the connection here might be.
Network latency for IOPS in a SAN. For small block sizes, I would think
latency would be even more of an issue than bandwidth when talking to a
ZFS based SAN. Then again, I suppose command tag queuing would coalesce
those so latency would not be as critical.
> Gordan
Received on Mon Sep 10 01:42:46 2012

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