Thinking of using ZFS/FBSD for a backup system

[Kris Kennaway]

CZUCZY Gergely wrote:
> On Tue, 08 Jul 2008 22:34:52 +0200
> Kris Kennaway <kris at FreeBSD.org> wrote:
>>> I've finetuned ZFS as much as I could, I've read every little tiny
>>> bit of hint/information/whatever that was available and I couldn't
>>> get rid of those kmem_size panics in -RELEASE and -STABLE.
>> Well, it's still almost certainly because you aren't setting
>> kmem_size high enough.  As you saw, that is the only thing I tuned
>> (disabling prefetch is just for performance in my environment).
>>
>> If you can't set it high enough because you don't have enough RAM,
>> that means your system does't have enough RAM to run ZFS, not that
>> ZFS is unstable.
> I've had a box with 2GB of memory for it, and around 5-6 filesystems.
> I've set kmem_size as large as it was allowed, not a bit smaller.
> 
> Where's the guide showing how much memory should I have for a setup?
> How can "enough memory" be determined for a setup, without having
> panics?

I don't know; empirically my setup is an upper bound.  How large was "as 
large as it was allowed" for you?

Kris