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From Alex Major <al3...@gmail.com>
Subject Re: Cassandra crashes
Date Fri, 06 Sep 2013 11:12:05 GMT
Have you changed the appropriate config settings so that Cassandra will run
with only 2GB RAM? You shouldn't find the nodes go down.

Check out this blog post
http://www.opensourceconnections.com/2013/08/31/building-the-perfect-cassandra-test-environment/,
it outlines the configuration settings needed to run Cassandra on 64MB
RAM and might give you some insights.


On Wed, Sep 4, 2013 at 9:44 AM, Jan Algermissen
<jan.algermissen@nordsc.com>wrote:

> Hi,
>
> I have set up C* in a very limited environment: 3 VMs at digitalocean with
> 2GB RAM and 40GB SSDs, so my expectations about overall performance are low.
>
> Keyspace uses replication level of 2.
>
> I am loading 1.5 Mio rows (each 60 columns of a mix of numbers and small
> texts, 300.000 wide rows effektively) in a quite 'agressive' way, using
> java-driver and async update statements.
>
> After a while of importing data, I start seeing timeouts reported by the
> driver:
>
> com.datastax.driver.core.exceptions.WriteTimeoutException: Cassandra
> timeout during write query at consistency ONE (1 replica were required but
> only 0 acknowledged the write
>
> and then later, host-unavailability exceptions:
>
> com.datastax.driver.core.exceptions.UnavailableException: Not enough
> replica available for query at consistency ONE (1 required but only 0
> alive).
>
> Looking at the 3 hosts, I see two C*s went down - which explains that I
> still see some writes succeeding (that must be the one host left,
> satisfying the consitency level ONE).
>
>
> The logs tell me AFAIU that the servers shutdown due to reaching the heap
> size limit.
>
> I am irritated by the fact that the instances (it seems) shut themselves
> down instead of limiting their amount of work. I understand that I need to
> tweak the configuration and likely get more RAM, but still, I would
> actually be satisfied with reduced service (and likely more timeouts in the
> client).  Right now it looks as if I would have to slow down the client
> 'artificially'  to prevent the loss of hosts - does that make sense?
>
> Can anyone explain whether this is intended behavior, meaning I'll just
> have to accept the self-shutdown of the hosts? Or alternatively, what data
> I should collect to investigate the cause further?
>
> Jan
>
>
>
>
>
>

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