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From Jan Algermissen <jan.algermis...@nordsc.com>
Subject Re: Recommended hardware
Date Tue, 24 Sep 2013 06:42:30 GMT
Tim,

On 23.09.2013, at 18:17, Tim Dunphy <bluethundr@gmail.com> wrote:

> Hello,
> 
> I am running Cassandra 2.0 on a 2gb memory 10 gb HD in a virtual "cloud" environment.
It's supporting a php application running on the same node.

I have played with C* (1.2 and 2.0) in a low-RAM environment the last month. The major insight
I gained is that it is not really possible to get C* to protect itself against incoming writes.
Apparently it will just keep sucking in writes until death - if it cannot flush the memtables
fast enough.
 
You could share with us the write/read behavior of your use case (how much, how often) and
whether you use SSDs or spinning disks. But aside from the specifics, I'd say that

- You need at least 4GB  RAM
- If you do not have SSDs, you need two disks, one for OS and commitlog, one for the data
- Give C* it's own 3+ nodes if you want to really investigate C* behavior (e.g. nodes talking
to each other, replication, CAS)
- Check whether your VMs have the storage directly attached (unlikely) or whether they share
with other VMs (which isn't optimal)

HTH,
Jan

> 
> Mostly this instance runs smoothly but runs low on memory. Depending on how much the
site is used, the VM will swap out sometimes excessively.
> 
> I realize this setup may not be enough to support a cassandra instance.
> 
> I was wondering if there were any "recommended hardware specs" someone could point me
to for both physical and virtual (cloud) type environments.
> 
> Thank you,
> Tim
> Sent from my iPhone


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