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Date:      Thu, 29 Apr 2010 10:56:31 -0600
From:      Scott Long <scottl@samsco.org>
To:        Tom Evans <tevans.uk@googlemail.com>
Cc:        Ollivier Robert <roberto@keltia.freenix.fr>, freebsd-current@freebsd.org
Subject:   Re: kmem_map too small: 3832475648 total allocated
Message-ID:  <E79134A9-2174-4905-85A6-ADAEC0EA7D66@samsco.org>
In-Reply-To: <n2m2e027be01004290844k51dd6060q77375e894ff4efc4@mail.gmail.com>
References:  <4BD8F7FA.2080103@jrv.org> <20100429145334.GB62822@roberto-al.eurocontrol.fr> <n2m2e027be01004290844k51dd6060q77375e894ff4efc4@mail.gmail.com>

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On Apr 29, 2010, at 9:44 AM, Tom Evans wrote:
> On Thu, Apr 29, 2010 at 3:53 PM, Ollivier Robert
> <roberto@keltia.freenix.fr> wrote:
>> According to James R. Van Artsdalen:
>>> system is a Core i7 975 (3.33 GHz x 4 cores 3x threads per core) =
with 12
>>> GB of RAM, a 2x2TB ZFS boot pool and a second (idle) pool of 16x2TB.
>>=20
>>> panic: kmem_malloc(131072): kmem_map too small: 3832475648 total =
allocated
>>=20
>> Apart from the fact that you must at least set vm.kmem_size to =
something like 2x your RAM, one rule of thumb I've seen discussed for =
ZFS is that you will need approximatively 1 GB of RAM per TB of data so =
you may be a bit short here to get optimal perfs.
>>=20
>=20
> Citation needed? I have a file server running amd64 8-STABLE with 4GB
> of RAM, 6 x 1.5 TB drives in raidz, and have never had any problems
> with memory usage. Are you saying that after my next update, adding
> another 6 x 1.5 TB drives, it will start being flaky and/or panicing
> with kmem_map too small errors?
>=20

I'm sorry, but I find it absolutely absurd that any filesystem has to =
wire down 2GB of RAM, and that the solution to panics is buy more RAM.

Scott




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