Re: [Advocacy] Re: 3ware 9650 tips

Re: [Advocacy] Re: 3ware 9650 tips

[Al Boldi]

Bryan J. Smith wrote:
> Off-topic, advocacy-level response ...
>
> On Mon, 2007-07-16 at 11:43 -0400, Joshua Baker-LePain wrote:
> > I do so wish that RedHat shared this view...
>
> I've been trying to convince them since Red Hat Linux 7 (and, later, 9)
> that they need to realize the limits of Ext3 at the enterprise end of
> the scalability spectrum -- you know, that whole market they are
> seemingly saying they are the king of and a replacement for Sun?  ;->
>
> The problem with Red Hat is that when anyone brings up an alternative to
> Ext3, Red Hat falls back to arguments against other filesystems, which
> is rather easy given the various compatibility issues with JFS (ported
> from OS/2, requiring a lot of inode compatibility hacks -- don't get me
> started with my experiences) and ReiserFS (utter lack of inode
> compatibility in structures, requiring kernel-level emulation, etc...
> that never seems to work, regardless of what the advocates say, let
> alone the almsota always "out-of-sync" off-line repair tools).
>
> But when you bring up XFS and its history of a stable, but advanced
> inode structure, quota support from day 1, POSIX ACLs from nearly day 1,
> and all the SGI team put into 2.5.3+ that is now stock kernel, they
> still try to dance.  One thing I always get is "oh, its extents don't
> perform well for /tmp or /var" or countless other arguments, of which I
> merely respond, "all the more reason to use Ext3 for those few
> filesystems, and XFS when Ext3 doesn't scale -- like for
> large /home, /export, etc... filesystems."  No matter how many times I
> put forth the argument that XFS complements Ext3, they seem to treat it
> as yet another JFS/ReiserFS argument.
>
> Hopeless?
>
> -- Bryan "one of the reasons I still deploy Solaris instead of RHEL for
> fileservers, even though RHL7+XFS and RHL9+XFS rocked (and are still
> rocking!)" Smith

XFS surely rocks, but it's missing one critical component: data=ordered
And that's one component that's just too critical to overlook for an 
enterprise environment that is built on data-integrity over performance.

So that's the secret why people still use ext3, and XFS' reliance on external 
hardware to ensure integrity is really misplaced.

Now, maybe when we get the data=ordered onto the VFS level, then maybe XFS 
may become viable for the enterprise, and ext3 may cease to be KING.


Thanks!

--
Al

Re: [Advocacy] Re: 3ware 9650 tips

[Matthew Wilcox]

On Mon, Jul 16, 2007 at 08:40:00PM +0300, Al Boldi wrote:
> XFS surely rocks, but it's missing one critical component: data=ordered
> And that's one component that's just too critical to overlook for an 
> enterprise environment that is built on data-integrity over performance.
> 
> So that's the secret why people still use ext3, and XFS' reliance on external 
> hardware to ensure integrity is really misplaced.
> 
> Now, maybe when we get the data=ordered onto the VFS level, then maybe XFS 
> may become viable for the enterprise, and ext3 may cease to be KING.

Wow, thanks for bringing an advocacy thread onto linux-fsdevel.  Just what
we wanted.  Do you have any insight into how to "get the data=ordered
onto the VFS level"?  Because to me, that sounds like pure nonsense.

-- 
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

[RFC] VFS: data=ordered (was: [Advocacy] Re: 3ware 9650 tips)

[Al Boldi]

Matthew Wilcox wrote:
> On Mon, Jul 16, 2007 at 08:40:00PM +0300, Al Boldi wrote:
> > XFS surely rocks, but it's missing one critical component: data=ordered
> > And that's one component that's just too critical to overlook for an
> > enterprise environment that is built on data-integrity over performance.
> >
> > So that's the secret why people still use ext3, and XFS' reliance on
> > external hardware to ensure integrity is really misplaced.
> >
> > Now, maybe when we get the data=ordered onto the VFS level, then maybe
> > XFS may become viable for the enterprise, and ext3 may cease to be KING.
>
> Wow, thanks for bringing an advocacy thread onto linux-fsdevel.  Just what
> we wanted.  Do you have any insight into how to "get the data=ordered
> onto the VFS level"?  Because to me, that sounds like pure nonsense.

Well, conceptually it sounds like a piece of cake, technically your guess is 
as good as mine.  IIRC, akpm once mentioned something like this.

But seriously, can you think of a technical reason why it shouldn't be 
possible to abstract data=ordered mode out into the VFS?


Thanks!

--
Al

Re: [RFC] VFS: data=ordered (was: [Advocacy] Re: 3ware 9650 tips)

[Matthew Wilcox]

On Mon, Jul 16, 2007 at 09:28:08PM +0300, Al Boldi wrote:
> Well, conceptually it sounds like a piece of cake, technically your guess is 
> as good as mine.  IIRC, akpm once mentioned something like this.

How much have you looked at the VFS?  There's nothing journalling-related
in the VFS right now.  ext3 and XFS share no common journalling code,
nor do I think that would be possible, due to the very different concepts
they have of journalling.

Here's a good hint:

$ find fs -type f |xargs grep -l journal_start
fs/ext3/acl.c
fs/ext3/inode.c
fs/ext3/ioctl.c
fs/ext3/namei.c
fs/ext3/resize.c
fs/ext3/super.c
fs/ext3/xattr.c
fs/ext4/acl.c
fs/ext4/extents.c
fs/ext4/inode.c
fs/ext4/ioctl.c
fs/ext4/namei.c
fs/ext4/resize.c
fs/ext4/super.c
fs/ext4/xattr.c
fs/jbd/journal.c
fs/jbd/transaction.c
fs/jbd2/journal.c
fs/jbd2/transaction.c
fs/ocfs2/journal.c
fs/ocfs2/super.c

JBD and JBD2 provide a journalling implementation that ext3, ext4 and
ocfs2 use.  Note that XFS doesn't, it has its own journalling code.

If you want XFS to support data=ordered, talk to the XFS folks.  Or
start picking through XFS yourself, of course -- you do have the source
code.

-- 
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

Re: [Advocacy] Re: 3ware 9650 tips

[Bryan J. Smith]

On Mon, 2007-07-16 at 11:48 -0600, Matthew Wilcox wrote:
> Wow, thanks for bringing an advocacy thread onto linux-fsdevel.  Just what
> we wanted.  Do you have any insight into how to "get the data=ordered
> onto the VFS level"?  Because to me, that sounds like pure nonsense.

First off, I have no idea who decided to respond to my post and CC:
linux-fsdevel on it.

In retrospect, secondly, I should have not posted my post to linux-raid
in the first place (is that list now mirrored to linux-fsdevel or
something?).  I was just sharing in my frustration of the lack of XFS
support by Red Hat.

So, lastly and in any case, my apologies to all, even if I did not
proliferate it to linux-fsdevel, it was probably not ideal for me to
post such to anything on vger.kernel.org (like linux-raid) in the first
place.


-- 
Bryan J. Smith         Professional, Technical Annoyance
mailto:b.j.smith@ieee.org   http://thebs413.blogspot.com
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