Elasticsearch configuration for uninterrupted indexing

Elastic Stack Elasticsearch
1

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana for
log analysis. I am using one machine (2 GB RAM, 2 CPUs) running logstash,
kibana and two instances of elasticsearch. Two other machines, each
running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did the
indexing (called the writer node) and the other node, was master = false
and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is stored
on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having one
reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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2

One of the main usage of having a data-less node is that it would act as a
coordinator between the other nodes. It will gather all the responses from
the other nodes/shards and reduce them into one.

In your case, the data-less node is gathering all the data from just one
node. In other words, it is not doing much since the reduce phase is
basically a pass-thru operation. With a two node cluster, I would say you
are better off having both machines act as full nodes.

Cheers,

Ivan

On Fri, Mar 21, 2014 at 5:04 AM, Rujuta Deshpande rujdesh@gmail.com wrote:

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana for
log analysis. I am using one machine (2 GB RAM, 2 CPUs) running logstash,
kibana and two instances of elasticsearch. Two other machines, each
running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did
the indexing (called the writer node) and the other node, was master =
false and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is
stored on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having one
reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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3

Hi,

Thank you for the response. However, in our scenario, both the nodes are on
the same machine. Our setup doesn't allow us to have two separate machines
for each node. Also, we're indexing logs using logstash. Sometimes, we have
to query data from the logs over a period of two or three months and then,
we're thrown an out of memory error. This affects the indexing that is
simultaneously going on and we lose events.

I'm not sure what configuration of elasticsearch will help achieve this.

Thanks,
Rujuta

On Friday, March 21, 2014 10:36:51 PM UTC+5:30, Ivan Brusic wrote:

One of the main usage of having a data-less node is that it would act as a
coordinator between the other nodes. It will gather all the responses from
the other nodes/shards and reduce them into one.

In your case, the data-less node is gathering all the data from just one
node. In other words, it is not doing much since the reduce phase is
basically a pass-thru operation. With a two node cluster, I would say you
are better off having both machines act as full nodes.

Cheers,

Ivan

On Fri, Mar 21, 2014 at 5:04 AM, Rujuta Deshpande <ruj...@gmail.com<javascript:>

wrote:

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana for
log analysis. I am using one machine (2 GB RAM, 2 CPUs) running logstash,
kibana and two instances of elasticsearch. Two other machines, each
running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did
the indexing (called the writer node) and the other node, was master =
false and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is
stored on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having one
reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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4

I do not think splitting the application into 2 separate JVMs will solve
your issues. Is the 2GB per JVM or the total of the machine? For analytic
applications, with multiples facets, 2 GBs might not be sufficient.

--
Ivan

On Sun, Mar 23, 2014 at 10:04 PM, Rujuta Deshpande rujdesh@gmail.comwrote:

Hi,

Thank you for the response. However, in our scenario, both the nodes are
on the same machine. Our setup doesn't allow us to have two separate
machines for each node. Also, we're indexing logs using logstash.
Sometimes, we have to query data from the logs over a period of two or
three months and then, we're thrown an out of memory error. This affects
the indexing that is simultaneously going on and we lose events.

I'm not sure what configuration of elasticsearch will help achieve this.

Thanks,
Rujuta

On Friday, March 21, 2014 10:36:51 PM UTC+5:30, Ivan Brusic wrote:

One of the main usage of having a data-less node is that it would act as
a coordinator between the other nodes. It will gather all the responses
from the other nodes/shards and reduce them into one.

In your case, the data-less node is gathering all the data from just one
node. In other words, it is not doing much since the reduce phase is
basically a pass-thru operation. With a two node cluster, I would say you
are better off having both machines act as full nodes.

Cheers,

Ivan

On Fri, Mar 21, 2014 at 5:04 AM, Rujuta Deshpande ruj...@gmail.comwrote:

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana for
log analysis. I am using one machine (2 GB RAM, 2 CPUs) running logstash,
kibana and two instances of elasticsearch. Two other machines, each
running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did
the indexing (called the writer node) and the other node, was master =
false and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is
stored on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having one
reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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5

Well it was for the entire machine. Now, I have changed it to a 4 GB
machine. Even 4 GB is not enough right now and I do face the same problem.
I am trying to benchmark the max/min Heap size I will have to allocate to
an elasticsearch instance to be able to achieve uninterrupted indexing
without running into memory errors. So, are you saying that the only
solution to this problem is an increase in memory ?

Thanks,
Rujuta

On Monday, March 24, 2014 9:56:25 PM UTC+5:30, Ivan Brusic wrote:

I do not think splitting the application into 2 separate JVMs will solve
your issues. Is the 2GB per JVM or the total of the machine? For analytic
applications, with multiples facets, 2 GBs might not be sufficient.

--
Ivan

On Sun, Mar 23, 2014 at 10:04 PM, Rujuta Deshpande <ruj...@gmail.com<javascript:>

wrote:

Hi,

Thank you for the response. However, in our scenario, both the nodes are
on the same machine. Our setup doesn't allow us to have two separate
machines for each node. Also, we're indexing logs using logstash.
Sometimes, we have to query data from the logs over a period of two or
three months and then, we're thrown an out of memory error. This affects
the indexing that is simultaneously going on and we lose events.

I'm not sure what configuration of elasticsearch will help achieve this.

Thanks,
Rujuta

On Friday, March 21, 2014 10:36:51 PM UTC+5:30, Ivan Brusic wrote:

One of the main usage of having a data-less node is that it would act as
a coordinator between the other nodes. It will gather all the responses
from the other nodes/shards and reduce them into one.

In your case, the data-less node is gathering all the data from just one
node. In other words, it is not doing much since the reduce phase is
basically a pass-thru operation. With a two node cluster, I would say you
are better off having both machines act as full nodes.

Cheers,

Ivan

On Fri, Mar 21, 2014 at 5:04 AM, Rujuta Deshpande ruj...@gmail.comwrote:

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana
for log analysis. I am using one machine (2 GB RAM, 2 CPUs) running
logstash, kibana and two instances of elasticsearch. Two other machines,
each running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did
the indexing (called the writer node) and the other node, was master =
false and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is
stored on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having
one reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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6

While it is possible to create an ES cluster with dedicated reader/writer
nodes, this is not the default and in many cases, dedication of nodes is
not required at all. ES has some better heuristics built in to relief the
admin from tedious jobs like setting up dedicated nodes.

So I wonder how you understand what a reader or a writer node is. Note, if
you connect a client to a node, this node does not necessarily do the heavy
work, it just forwards automatically the requests to the nodes that hold
the shards.

You should use replica level > 0 to distribute the query load. Replica
levels are duplicating shards just because of this - to allow better
distributed forwarding of search requests, and to allow some resilience in
case of node failures.

256m heap is very small for the massive Elasticsearch filter queries that
Kibana uses.

Jörg

On Fri, Mar 21, 2014 at 1:04 PM, Rujuta Deshpande rujdesh@gmail.com wrote:

Hi,

I am setting up a system consisting of elasticsearch-logstash-kibana for
log analysis. I am using one machine (2 GB RAM, 2 CPUs) running logstash,
kibana and two instances of elasticsearch. Two other machines, each
running logstash-forwarder are pumping logs into the ELK system.

The reasoning behind using two ES instances was this - I needed one
uninterrupted instance to index the incoming logs and I also needed to
query the currently existing indices. However, I didn't want any complex
querying to result in loss of events owing to Out of Memory Errors because
of excessive querying.

So, one elasticsearch node was master = true and data = true which did
the indexing (called the writer node) and the other node, was master =
false and data = false (this was the workhorse or reader node) .

I assumed that, in cases of excessive querying, although the data is
stored on the writer node, the reader node will query the data and all the
processing will take place on the reader as a result of which issues like
out of memory error etc will be avoided and uninterrupted indexing will
take place.

However, while testing this, I realized that the reader hardly uses the
heap memory ( Checked this in Marvel ) and when I fire a complex search
query - which was a search request using the python API where the 'size'
parameter was set to 10000, the writer node throws an out of memory error,
indicating that the processing also takes place on the writer node only. My
min and max heap size was set to 256m for this test. I also ensured that I
was firing the search query to the port on which the reader node was
listening (Port 9200). The writer node was running on Port 9201.

Was my previous understanding of the problem incorrect - i.e. having one
reader and one writer node, doesn't help in uninterrupted indexing of
documents? If this is so, what is the use of having a separate workhorse or
reader node?

My eventual aim is to be able to query elasticsearch and fetch large
amounts of data at a time without interrupting/slowing down the indexing of
documents.

Thank you.

Rujuta

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