

Native ZFS for Linux - spahl
http://zfsonlinux.org/

======
wnoise
Sort of.

From the FAQ:

1.3 How do I mount the file system?

You can’t… at least not today. While we have ported the majority of the ZFS
code to the Linux kernel that does not yet include the ZFS posix layer. The
only interface currently available from user space is the ZVOL virtual block
device.

~~~
dataguy
... ZPL, so the Z POSIX Layer, is the really awesome thing. Virtual block
device access is neat, though. I wonder when the first one starts building a
high performance data base project based on virtual blocks in zfs for linux.
Could be interesting.

~~~
ssmoot
ZVOLs are block devices. So you could install another fs on top of one. Or
more usefully export it as an iSCSI target.

~~~
ithkuil
sorry for the stupid question, but what features I get with ZVOLS exported as
iSCSI/AoE versus exporting a LVM device?

------
binomial
What I'd love is for the L2ARC system built on top of ZFS to be ported as
well. That's a killer feature for web applications. Basically, it can extend
your cache to include an SSD, but manage that all internally, so you just use
your database as usual on top of ZFS and let it handle all the caching and
moving less used data from SSD to disk and vice versa, and of course the usual
filesystem caching in RAM as well.

Though you could get similar functionality by using membase at the expense of
being limited to get/set operations (it's a K/V store).

~~~
kmavm
See Facebook's FlashCache if you get tired of waiting:
<http://www.facebook.com/note.php?note_id=388112370932>

~~~
wmf
Or bcache: <http://bcache.evilpiepirate.org/FrontPage>

~~~
binomial
Very nice, thanks for both.

------
steve19
_It has been successfully ported to FreeBSD and now there is a functional
Linux ZFS kernel port too_

So this is a port and therefor CDDL licesned and no able to be merged into the
mainline Linux Kernel, right?

Is ZFS still a hot commodity with BTRfs just around the corner?

~~~
ssmoot
I've heard about btrfs being "just around the corner" for a good while now.
ZFS on Nexenta and even FreeBSD is pretty robust. It's a great storage
platform. I wouldn't let waiting on a stable btrfs make my SAN/NAS decisions
for me.

The other concern in that realm is that when you're centralizing storage
concerns to lower costs, boost performance and increase reliability you don't
want software issues or corruption to take down your entire business.

ZFS can be a painful enough learning curve when it comes to that environment.
I wouldn't trust btrfs until it's been stable for a couple years there. And
outside of that environment, there are plenty of good stable alternatives for
the DAS space. While ZFS is nice there, and I'm sure btrfs would be as well,
that's not the bread and butter for these systems.

~~~
Andys
I believe btrfs comes with Ubuntu 10.10

~~~
alphabeat
Can you provide a source for that? Sounds exciting.

~~~
spahl
It was supposed to get into 10.10 for testing but according to the blueprint
it was deferred
([https://blueprints.launchpad.net/ubuntu/+spec/foundations-m-...](https://blueprints.launchpad.net/ubuntu/+spec/foundations-
m-btrfs-support)).

------
nivertech
Can you implement shared filesystem on multiple EC2 istances with this ZFS
implementation? Which Linux distro is best for it?

~~~
spahl
ZFS is not a distributed filesystem. What you can do is export it over nfs for
example. It also has replication features with send/receive but I don't think
this implementation supports it.

Edit: I notice that a lot of people think ZFS is a cluster/distributed
filesystem. I don't understand where they get this idea.

~~~
nivertech
Shared filesystem is not the same as cluster/distributed filesystem. It's mere
a management convenience and letting legacy code work without changes.

There is a problem on Amazon EC2, that you can mount EBS (Elastic Block
Storage) only to one EC2 instance at a time.

I was told by several people (including some from Sun), that the only way to
mount the same EBS instance to multiple EC2 instances is to use OpenSolaris
and ZFS. I don't think this solution involves NFS.

Anyway now when ZFS almost ported to Linux, it would be great to check this
issue again (requires ZPL).

~~~
carson
There is no way of attaching EBS volumes to multiple instances, see the EBS
API overview:
[http://docs.amazonwebservices.com/AWSEC2/2010-08-31/Develope...](http://docs.amazonwebservices.com/AWSEC2/2010-08-31/DeveloperGuide/ebs-
api-overview.html)

What might work if you wanted to do this is to mount the EBS volume to an
instance and then expose the volume using a network block device to multiple
instances. Seems convoluted. Being able to attach EBS to multiple instances
may be something Amazon will add if there is enough interest.

------
leif
So...when can I use this to share data between a BSD and a Linux machine?

------
c00p3r
If it isn't backed by RedHat it is useless. Redhat have his amazing triple
develop/test/bugfix process Fedora-development->Fedora->RHEL. But even Fedora
is quite stable.

~~~
c00p3r
to stupid down-voters: try to count what amount of testing a standalone
package gets compared to the package which is a part of Fedora Project? In
term of number of installations? community involved? Fedora's team and
infrastructure?

~~~
wmf
Doesn't Ubuntu have more users than Fedora? You really sound like you're
trolling. Maybe you should have said "if it isn't backed by a major distro
it's useless".

~~~
c00p3r
More than Fedora + CentOS + RHEL?

Are web-hosting or shared-hosting providers using Ubuntu?

What do you thing Amazon or RackSpace are using?

~~~
moe
[http://www.google.com/insights/search/#q=%20Centos%2C%20RedH...](http://www.google.com/insights/search/#q=%20Centos%2C%20RedHat%2C%20Fedora%2C%20RHEL%2C%20Ubuntu&cmpt=q)

RPM based distros generally have a tough standing since Ubuntu began to
eclipse everything else in terms of popularity.

~~~
c00p3r
OK. I'll try to explain.

This search results showing that there are a lot of Linux home users who're
using Ubuntu because it is most popular _Desktop_ distro. Its popularity in a
large extend due to money Canonical spent on promotion. (Remember free
shipping of CD's and other actions)

But if you're considering a server segment, there are traditionally CentOS,
RHEL or Fedora. Or even that stupid Unbreakable Linux. Why it is so? (Because
it got that way!)

First, because most of really important key developers, like mr. Ulrich
Drepper, works for RedHat or with Redhat. Redhat also actively supported by
IBM, that's why RHEL is a such huge success.

Second, since RHEL4, when they made that stupid decision to maintain all the
patches by themselves (RHEL4's kernel source rpm had up to 300 patches in it,
but I'm not quite sure you know what it is all about.)

Now, they work with a mainstream kernel developers, so all their code got a
most extensive testing possible. This is what Google's Linux engineers still
cannot understand - the best testing and bug hunting is in primary linux
source tree.

So, what about Ubuntu? Compared to Fedora it is outdated, very conservative,
desktop-oriented distro for an average mediocre user. I don't want to go
deeper and try to compare source packages of key components, such as kernel,
glibc and related, but I'm pretty sure there are different set of patches. One
can compare common packages like perl, python, erlang, gcc, php by themselves.

Conclusion? OK, 3-5 years ago using Ubuntu or Debian as a server instead of
Fedora-derived distros was a sign of non-professionalism, if not a fanboyism
or even ignorance. What changed today? Almost nothing. Ubuntu is following the
same conservative policies. There are some so-called server editions of
Ubuntu, but it is rather a marketing movement.

And, you might be surprised, but key kernel developers are using Fedora. =)

~~~
moe
_using Ubuntu or Debian as a server instead of Fedora-derived distros was a
sign of non-professionalism_

Funny. In my circles it's considered a sign of masochism to run a RPM based
distro in this day & age. To each their own, let's keep the evangelism off HN.

~~~
c00p3r
Please re-read the part about RHEL4 and kernel patches. Take into account that
some people were using Oracle and Informix before any Unbreakable things.

~~~
moe
How does your response relate to what I just said?

