[email protected] wrote:
> Hi all,
>
> this some kind of Off-Topic since it has nothing to do with LFS at all. I
> send this to this list because I know that there are quite a lot geeks and
> experienced people out there who may have a hint for me.
>
> Have you ever seen a machine which has too much RAM installed? We have a
> brand new HP (DL380G6) server here with 48G RAM installed. It has an p410i
> and a p800 SAS controller connected to a MSA70 with 1TB usable disk space.
> There are 2 Quad-Core-Xeon (X5560) with hyperthreading (a total of 16 CPUs).
>
> As an OS there is s SuSE SLES10 installed and as DB-Software (because of
> which we have this machine) Oracle10g.
>
> The problem:
> When we create a file which is 32GByte large (for instance using dd
> if=/dev/null of=test.dat...) the copy process runs very fast up to round
> about 29-30GB slows down quite immediatly and the workload increases up to
> loadavg=35 or so. It finally results in a non-responding machine where we
> can only press the reset-button.
>
> What we did:
> Adding the mentioned 30GB plus the rest what the OS itself is using it
> adds up to quite exact 32GB. We removed 6 of the 12 RAM modules (every has
> 4GB) so that the machine now has less that 32GB RAM (exact 24GB). The dd
> command runs quite fast until the file was created and nothing special is
> seen on the machine - everything worked as expected.
>
> Do you have an idea what the 32GB-limit could be? Or what could make the
> machine to behave the way it does?
>
> Our next step will be to test that all with the 64-bit stuff but it should
> work on 32bit too, isn't it?
There are a couple of things to consider. Is this a 32-bit or 64-bit
OS? It was not clear in your message. If it is a 32-bit system, you
need to have the kernel enabled for
CONFIG_HIGHMEM4G:
Select this if you have a 32-bit processor and between 1 and 4
gigabytes of physical RAM.
or
CONFIG_HIGHMEM64G:
Select this if you have a 32-bit processor and more than 4
gigabytes of physical RAM.
It you have 64-bit system, make sure you have plenty of swap space. Try
setting up 100G and see if that makes a difference. You can try that
for a 32-bit system too.
-- Bruce
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