write load while idle?

[Keith Freeman <8f...@gmail.com>]

I have a 3-node cluster running 1.2.8, and with no clients connected 
(for about an hour) opscenter is showing a heartbeat-like pattern for 
total writes in the "Cluster Reads & Writes" panel on the dashboard 
ranging from about 10/sec to 26/sec.  Total reads on the other hand are 
showing a straight line hovering just barely above 0/sec.  There are no 
compactions, etc. (the logs are totally quiet).

Is this normal?  I'm new to cassandra so maybe this is normal but I 
couldn't find an explanation in the docs and it seems pretty high for an 
idle system.

Re: write load while idle?

[sankalp kohli <ko...@gmail.com>]

Storing OpsCenter data on the same cluster you are monitoring might not
work well. I had an issue in which Cassandra had issues and OpsCenter wont
load. You might want to store this data in some other cluster or create a
fake DC and assign OpsCenter data to that fake DC.


On Thu, Aug 22, 2013 at 4:55 PM, Nate McCall <na...@thelastpickle.com> wrote:

> Yep - OpsCenter stores it's own data in Cassandra. Thus the activity.
>
> You could also turn on debug logging for StorageProxy on one of the nodes
> if you really want to know.
>
>
> On Thu, Aug 22, 2013 at 6:18 PM, Robert Coli <rc...@eventbrite.com> wrote:
>
>> On Fri, Aug 16, 2013 at 4:46 PM, Keith Freeman <8f...@gmail.com> wrote:
>>
>>> I have a 3-node cluster running 1.2.8, and with no clients connected
>>> (for about an hour) opscenter is showing a heartbeat-like pattern for total
>>> writes in the "Cluster Reads & Writes" panel on the dashboard ranging from
>>> about 10/sec to 26/sec.  Total reads on the other hand are showing a
>>> straight line hovering just barely above 0/sec.  There are no compactions,
>>> etc. (the logs are totally quiet).
>>>
>>> Is this normal?  I'm new to cassandra so maybe this is normal but I
>>> couldn't find an explanation in the docs and it seems pretty high for an
>>> idle system.
>>>
>>
>> That doesn't seem normal to me, but then I don't run Opscenter. Have you
>> tried turning off OpsCenter to see if it changes?
>>
>> Also, those writes have to go.. somewhere? If you inspect memtables or
>> flush, where do you see data being stored or flushed?
>>
>> =Rob
>>
>>
>

Re: write load while idle?

[Nate McCall <na...@thelastpickle.com>]

Yep - OpsCenter stores it's own data in Cassandra. Thus the activity.

You could also turn on debug logging for StorageProxy on one of the nodes
if you really want to know.


On Thu, Aug 22, 2013 at 6:18 PM, Robert Coli <rc...@eventbrite.com> wrote:

> On Fri, Aug 16, 2013 at 4:46 PM, Keith Freeman <8f...@gmail.com> wrote:
>
>> I have a 3-node cluster running 1.2.8, and with no clients connected (for
>> about an hour) opscenter is showing a heartbeat-like pattern for total
>> writes in the "Cluster Reads & Writes" panel on the dashboard ranging from
>> about 10/sec to 26/sec.  Total reads on the other hand are showing a
>> straight line hovering just barely above 0/sec.  There are no compactions,
>> etc. (the logs are totally quiet).
>>
>> Is this normal?  I'm new to cassandra so maybe this is normal but I
>> couldn't find an explanation in the docs and it seems pretty high for an
>> idle system.
>>
>
> That doesn't seem normal to me, but then I don't run Opscenter. Have you
> tried turning off OpsCenter to see if it changes?
>
> Also, those writes have to go.. somewhere? If you inspect memtables or
> flush, where do you see data being stored or flushed?
>
> =Rob
>
>

Re: write load while idle?

[Robert Coli <rc...@eventbrite.com>]

On Fri, Aug 16, 2013 at 4:46 PM, Keith Freeman <8f...@gmail.com> wrote:

> I have a 3-node cluster running 1.2.8, and with no clients connected (for
> about an hour) opscenter is showing a heartbeat-like pattern for total
> writes in the "Cluster Reads & Writes" panel on the dashboard ranging from
> about 10/sec to 26/sec.  Total reads on the other hand are showing a
> straight line hovering just barely above 0/sec.  There are no compactions,
> etc. (the logs are totally quiet).
>
> Is this normal?  I'm new to cassandra so maybe this is normal but I
> couldn't find an explanation in the docs and it seems pretty high for an
> idle system.
>

That doesn't seem normal to me, but then I don't run Opscenter. Have you
tried turning off OpsCenter to see if it changes?

Also, those writes have to go.. somewhere? If you inspect memtables or
flush, where do you see data being stored or flushed?

=Rob