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Date: Sun, 06 Jan 2008 15:27:18 +0100
From: Kris Kennaway <kris@FreeBSD.org>
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To: Ivan Voras <ivoras@freebsd.org>
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Cc: freebsd-current@freebsd.org
Subject: Re: When will ZFS become stable?
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Ivan Voras wrote:
> Kris Kennaway wrote:
> 
>> kmem problems are just tuning.  They are not indicative of stability 
>> problems in ZFS.  
> 
> I disagree - anything that causes a panic is a stability problem. Panics 
> persist AFTER the tunings (for i386 certainly, and there are unsolved 
> reports about it on amd64 also) and are present even when driving kmem 
> size to the maximum. The tunings *can not solve the problems* currently, 
> they can only delay the time until they appear, which, by Murphy, often 
> means "sometime around midnight at Saturday".

That's an assertion directly contradicted by my experience running a 
heavily loaded 8-core i386 package builder.  Please explain in detail 
the steps you have taken to tune your kernel.  Do you have the vm_kern.c 
patch applied?

 > See also the possibility
 > of deadlocks in the ZIL, reported by some users.

Yes, this is an outstanding issue.  There are a couple of others I run 
into in the above configuration, but kmem panics aren't among them.

>> Please report any further non-kmem panics you experience.
> 
> I did, once to Pawel and once to the lists. Pawel couldn't help me and 
> nobody responded on the lists. Can you perform a MySQL read-write 
> benchmark on one of the 8-core machines with database on ZFS for about 
> an hour without pause? On a machine with 2 GB (or less) of RAM, 
> preferrably? I've seen problems on i386 but maybe they are also present 
> on amd64.

I am not set up to test this right now.

Kris