When will ZFS become stable?

Kris Kennaway kris at FreeBSD.org
Sun Jan 6 08:22:09 PST 2008


Maciej Suszko wrote:
> Kris Kennaway wrote:
>> Maciej Suszko wrote:
>>> Kris Kennaway wrote:
>>>> Ivan Voras wrote:
>>>>> On 06/01/2008, Peter Schuller <peter.schuller at infidyne.com> wrote:
>>>>>>> This number is not so large. It seems to be easily crashed by
>>>>>>> rsync, for example (speaking from my own experience, and also
>>>>>>> some of my colleagues).
>>>>>> I can definitely say this is not *generally* true, as I do a lot
>>>>>> of rsyncing/rdiff-backup:ing and similar stuff (with many files /
>>>>>> large files) on ZFS without any stability issues. Problems for me
>>>>>> have been limited to 32bit and the memory exhaustion issue rather
>>>>>> than "hard" issues.
>>>>> It's not generally true since kmem problems with rsync are often
>>>>> hard to repeat - I have them on one machine, but not on another,
>>>>> similar machine. This nonrepeatability is also a part of the
>>>>> problem.
>>>>>
>>>>>> But perhaps that's all you are referring to.
>>>>> Mostly. I did have a ZFS crash with rsync that wasn't kmem
>>>>> related, but only once.
>>>> kmem problems are just tuning.  They are not indicative of
>>>> stability problems in ZFS.  Please report any further non-kmem
>>>> panics you experience.
>>> I agree that ZFS is pretty stable itself. I use 32bit machine with
>>> 2gigs od RAM and all hang cases are kmem related, but the fact is
>>> that I haven't found any way of tuning to stop it crashing. When I
>>> do some rsyncing, especially beetwen different pools - it hangs or
>>> reboots - mostly on bigger files (i.e. rsyncing ports tree with
>>> distfiles). At the moment I patched the kernel with
>>> vm_kern.c.2.patch and it just stopped crashing, but from time to
>>> time the machine looks like beeing freezed for a second or two,
>>> after that it works normally. Have you got any similar experience?
>> That is expected.  That patch makes the system do more work to try
>> and reclaim memory when it would previously have panicked from lack
>> of memory.  However, the same advice applies as to Ivan: you should
>> try and tune the memory parameters better to avoid this last-ditch
>> sitation.
> 
> As Ivan said - tuning kmem_size only delay the moment system crash,
> earlier or after it happens - that's my point of view.

So the same question applies: exactly what steps did you take to tune 
the memory parameters?  Extracting this information from you guys 
shouldn't be as hard as this :)

Kris



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