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From Robin Verlangen <ro...@us2.nl>
Subject Re: Cassandra node going down
Date Fri, 14 Sep 2012 14:12:58 GMT
Cassandra writes to memtables, that will get flushed to disk when it's
time. That might be because of running out of memory (the log message you
just posted), on a shutdown, or at other times. That's why you're using
memory while writing.

You seem to be running on AWS, are you sure your data location is on the
right disk? Default is /var/lib/cassandra/data

Best regards,

Robin Verlangen
*Software engineer*
*
*
W http://www.robinverlangen.nl
E robin@us2.nl

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2012/9/14 rohit reddy <rohit.kommareddy@gmail.com>

> Hi Robin,
>
> I had checked that. Our disk size is about 800GB, and the total data size
> is not more than 40GB. Even if all the data is stored in one node, this
> won't happen.
>
> I'll try to see if the disk failed.
>
> Is this anything to do with VM memory?.. cause this logs suggests that..
> Heap is 0.7515559786053904 full.  You may need to reduce memtable and/or
> cache sizes.  Cassandra will now flush up to the two largest memtables to
> free up memory.  Adjust flush_largest_memtables_at threshold in
> cassandra.yaml if you don't want Cassandra to do this automatically
>
> But, i'm only testing writes, there are no reads on the cluster. Will the
> writes require so much memory. A large instance has 7.5GB, so by default
> cassandra allocates about 3.75 GB for the VM.
>
>
>
> On Fri, Sep 14, 2012 at 6:58 PM, Robin Verlangen <robin@us2.nl> wrote:
>
>> Hi Robbit,
>>
>> I think it's running out of disk space, please verify that (on Linux: df
>> -h ).
>>
>> Best regards,
>>
>> Robin Verlangen
>> *Software engineer*
>> *
>> *
>> W http://www.robinverlangen.nl
>> E robin@us2.nl
>>
>> Disclaimer: The information contained in this message and attachments is
>> intended solely for the attention and use of the named addressee and may be
>> confidential. If you are not the intended recipient, you are reminded that
>> the information remains the property of the sender. You must not use,
>> disclose, distribute, copy, print or rely on this e-mail. If you have
>> received this message in error, please contact the sender immediately and
>> irrevocably delete this message and any copies.
>>
>>
>>
>> 2012/9/14 rohit reddy <rohit.kommareddy@gmail.com>
>>
>>> Hi,
>>>
>>> I'm facing a problem in Cassandra cluster deployed on EC2 where the node
>>> is going down under write load.
>>>
>>> I have configured a cluster of 4 Large EC2 nodes with RF of 2.
>>> All nodes are instance storage backed. DISK is RAID0 with 800GB
>>>
>>> I'm pumping in write requests at about 4000 writes/sec. One of the node
>>> went down under this load. The total data size in each node was not more
>>> than 7GB
>>> Got the following WARN messages in the LOG file...
>>>
>>> 1. setting live ratio to minimum of 1.0 instead of 0.9003153296009601
>>> 2. Heap is 0.7515559786053904 full.  You may need to reduce memtable
>>> and/or cache sizes.  Cassandra will now flush up to the two largest
>>> memtables to free up memory.  Adjust flush_largest_memtables_at threshold
>>> in cassandra.yaml if you don't want Cassandra to do
>>> this automatically
>>> 3. WARN [CompactionExecutor:570] 2012-09-14 11:45:12,024
>>> CompactionTask.java (line 84) insufficient space to compact all requested
>>> files
>>>
>>> All cassandra settings are default settings.
>>> Do i need to tune anything to support this write rate?
>>>
>>> Thanks
>>> Rohit
>>>
>>>
>>
>

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