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Re: Major XFS problems...

To: Chris Wedgwood <cw@xxxxxxxx>
Subject: Re: Major XFS problems...
From: Jakob Oestergaard <jakob@xxxxxxxxxxxxx>
Date: Wed, 8 Sep 2004 22:21:17 +0200
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <20040908192652.GA21082@xxxxxxxxxxxxxxxxxxxxx>
References: <20040908133954.GB390@xxxxxxxxxxxxx> <20040908192652.GA21082@xxxxxxxxxxxxxxxxxxxxx>
Sender: linux-xfs-bounce@xxxxxxxxxxx
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On Wed, Sep 08, 2004 at 12:26:52PM -0700, Chris Wedgwood wrote:
> On Wed, Sep 08, 2004 at 03:39:55PM +0200, Jakob Oestergaard wrote:
> 
> > *) ext3 - no-go, because quota isn't journalled
> 
> there are patches for that

Would *you* base a production environment on that ?   ;)

> > *) reiserfs - no-go, because of lack of quota
> 
> i was pretty sure this was merged, if not there are patches for that
> too

I've been corrected on that one; there *is* quota in reiserfs, but it is
not journalled (but there are rumers of patches for that as well).

We *need* the server to come up quickly after a crash or UPS failure.
Checking quota for the better part of a day is unacceptable.

> 
> > Some 4-8 hours after the backup has started, the dreaded
> > 'debug.c:106' message will appear (at some random place thru the
> > filesystem - it is not a consistent error in one specific location
> > in the filesystem), and the server will need a reboot.
> 
> have you run vmstat duing the backup to see what is going on here?
> checking /proc/meminfo periodically might also be useful.  im guessing
> you're getting massive amounts of slab being used from the dcache and
> runing low on low-memory and coupled with page-cache pressure
> something is getting upset...  (this was much more apparent in 2.4.x,
> i've not seen it for a long time in 2.6.x though)

Your guess is correct. More details are in Anders' previous posting to
LKML:

http://lkml.org/lkml/2004/8/24/53

> 
> how much ram does the machine have and are you using highmem?

2.5G RAM IIRC - but slab is in lowmem so the machine will barf when it
reaches ~850MB slab.

> 
> > Does anyone actually use XFS for serious file-serving?  (yes, I run
> > it on my desktop at home and I don't have problems there - such
> > reports are not really relevant).
> 
> plenty of people.  some of them would claim a few hungred GB isn't
> very serious either.

There seems to be a common trend that NFS+XFS+SMP is causing this. I
suppose that could explain some of that.

Could be, that the problem is not in XFS at all...

Anyway; hopefully Anders will get some testing done in this respect
tomorrow, then we'll know more.

> > Is anyone actually maintaining/bugfixing XFS?
> 
> yes

Hey, I had to ask  ;)

...
> netapp hardware is nice (and their nfs works great) --- but it costs a
> lot more typically

Thanks for your feedback!

-- 

 / jakob


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