Service discovery in the Cassandra cluster

[Roman Naumenko]

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.

This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?

Thanks,

—
Roman
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[Jon Haddad]

Sure, you could use DNS. Where does it say IP addresses are a requirement?

Post by Roman Naumenko
If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

---------------------------------------------------------------------
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For additional commands, e-mail: user-***@cassandra.apache.org

[daemeon reiydelle]

Yes, you can use host names. That merely adds another level of
configuration. When using terraform, I often use node names like
<mumble><nth node> and just use those. They are only routable within the
region/VPC but are in fact already in dns. You do have to watch out as if
you change the seeds (in tf) or the cluster can get terminated and rebuild.
If you have a way to capture these (you can do it in ansible, I had been
told it is really hard to do in Chef/Puppet) then your cms can just adjust
the xml as needed without fussing with route53.


*.......*



*Daemeon C.M. ReiydelleUSA (+1) 415.501.0198London (+44) (0) 20 8144 9872*

Post by Jon Haddad
Sure, you could use DNS. Where does it say IP addresses are a requirement?

Post by Roman Naumenko
If I understand how Cassandra nodes work, they must contain a list of

seed’s IP addressed in config file.

Post by Roman Naumenko
This requirement makes cluster setup unnecessarily complicated. Is it

possible to use DNS name for seed nodes?

Post by Roman Naumenko
Thanks,
—
Roman
---------------------------------------------------------------------

---------------------------------------------------------------------

[Roman Naumenko]

The docs mention IP addresses everywhere.

http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html>
Promote an existing node to a seed node by adding its IP address to -seeds list and remove (demote) the IP address of the dead seed node from the cassandra.yaml file for each node in the cluster.

http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html>
Note the Address of the dead node; it is used in step 5.

http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html>

num_tokens: recommended value: 256
-seeds: internal IP address of each seed node

I saw also hostnames mentioned few times, but it just makes it even more confusing.

—
Roman

Sure, you could use DNS. Where does it say IP addresses are a requirement?

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

[Jon Haddad]

The in-tree docs do not mention this anywhere, and even have some of the answers you’re asking:

https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds <https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds>

The DataStax docs are maintained outside of the project, you’ll have to ask them why they’re wrong or misleading.

Jon

Post by Roman Naumenko
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html>
Promote an existing node to a seed node by adding its IP address to -seeds list and remove (demote) the IP address of the dead seed node from the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html>
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html>

num_tokens: recommended value: 256
-seeds: internal IP address of each seed node

I saw also hostnames mentioned few times, but it just makes it even more confusing.
—
Roman

Sure, you could use DNS. Where does it say IP addresses are a requirement?

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

[Roman Naumenko]

Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic replacing seed nodes or what not.

—
Roman

Post by Jon Haddad
https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds <https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds>
The DataStax docs are maintained outside of the project, you’ll have to ask them why they’re wrong or misleading.
Jon

Post by Roman Naumenko
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html>
Promote an existing node to a seed node by adding its IP address to -seeds list and remove (demote) the IP address of the dead seed node from the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html>
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html>

num_tokens: recommended value: 256
-seeds: internal IP address of each seed node

I saw also hostnames mentioned few times, but it just makes it even more confusing.
—
Roman

Sure, you could use DNS. Where does it say IP addresses are a requirement?

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

[Jon Haddad]

Why do you have to figure out what’s up w/ them by accident? You’ve gotten all the information you need. Seeds are used to get the initial state of the cluster and as an optimization to spread gossip faster. That’s it.

Post by Roman Naumenko
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic replacing seed nodes or what not.
—
Roman

Post by Jon Haddad
https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds <https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds>
The DataStax docs are maintained outside of the project, you’ll have to ask them why they’re wrong or misleading.
Jon

Post by Roman Naumenko
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html>
Promote an existing node to a seed node by adding its IP address to -seeds list and remove (demote) the IP address of the dead seed node from the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html>
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html>

num_tokens: recommended value: 256
-seeds: internal IP address of each seed node

I saw also hostnames mentioned few times, but it just makes it even more confusing.
—
Roman

Sure, you could use DNS. Where does it say IP addresses are a requirement?

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

[Roman Naumenko]

Lol yeah, why
I guess I run some ec2 instances, drop some cassandra deb packages on 'em -
the thing will figure out how to run...

Also, how would you get "initial state of the cluster" if the cluster... is
being initialized?
Or that's easy, according to the docs - just hardcode some seed IPs into
each node, lol

It's all kinda funny, but in a sad way.

Post by Jon Haddad
Why do you have to figure out what’s up w/ them by accident? You’ve
gotten all the information you need. Seeds are used to get the initial
state of the cluster and as an optimization to spread gossip faster.
That’s it.
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic
replacing seed nodes or what not.
—
Roman
The in-tree docs do not mention this anywhere, and even have some of the
https://cassandra.apache.org/doc/latest/faq/index.html?
highlight=seed#what-are-seeds
The DataStax docs are maintained outside of the project, you’ll have to
ask them why they’re wrong or misleading.
Jon
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/
cassandra/operations/ops_replace_seed_node.html
Promote an existing node to a seed node by adding its IP address to -seeds
list and remove (demote) the IP address of the dead seed node from the
cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/
cassandra/operations/ops_replace_node_t.html
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/
initialize/initializeSingleDS.html
num_tokens: recommended value: 256
-seeds: internal IP address of each seed node
I saw also *hostnames *mentioned few times, but it just makes it even
more confusing.
—
Roman
Sure, you could use DNS. Where does it say IP addresses are a requirement?
If I understand how Cassandra nodes work, they must contain a list of
seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it
possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

[Steve Robenalt]

Hi Roman,

I'm assuming you were intending your first statement to be in jest, but
it's really not that hard to startup a Cassandra cluster. The defaults are
pretty usable, so if all you want to do is set the IPs and start it up, the
cluster probably will just take care of everything else.

So I jest a little bit too. It's normally desirable to set up storage
properly for your database, and there's a few options for which you might
want to change the defaults, such as the snitch.

Still, if that means you only need to take note of of a couple of IPs and
designate them as seeds so your cluster can mostly manage itself, you can
say that's sad, but I'd say it's a small price to pay for all that you
don't have to do.

Steve

Post by Roman Naumenko
Lol yeah, why
I guess I run some ec2 instances, drop some cassandra deb packages on 'em
- the thing will figure out how to run...
Also, how would you get "initial state of the cluster" if the cluster...
is being initialized?
Or that's easy, according to the docs - just hardcode some seed IPs into
each node, lol
It's all kinda funny, but in a sad way.

Post by Jon Haddad
Why do you have to figure out what’s up w/ them by accident? You’ve
gotten all the information you need. Seeds are used to get the initial
state of the cluster and as an optimization to spread gossip faster.
That’s it.
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic
replacing seed nodes or what not.
—
Roman
The in-tree docs do not mention this anywhere, and even have some of the
https://cassandra.apache.org/doc/latest/faq/index.html?highl
ight=seed#what-are-seeds
The DataStax docs are maintained outside of the project, you’ll have to
ask them why they’re wrong or misleading.
Jon
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra
/operations/ops_replace_seed_node.html
Promote an existing node to a seed node by adding its IP address to
-seeds list and remove (demote) the IP address of the dead seed node from
the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra
/operations/ops_replace_node_t.html
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initiali
ze/initializeSingleDS.html
num_tokens: recommended value: 256
-seeds: internal IP address of each seed node
I saw also *hostnames *mentioned few times, but it just makes it even
more confusing.
—
Roman
Sure, you could use DNS. Where does it say IP addresses are a requirement?
If I understand how Cassandra nodes work, they must contain a list of
seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it
possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

--
* Steve Robenalt Software Architect, HighWire Press, Inc. *
www.highwire.org| Los Gatos, CA| Belfast, NI| Brighton, UK
<https://www.linkedin.com/company-beta/1797/>
<http://twitter.com/highwirepress>

*HighWire Summer Publishers' Meeting, London, June 12-13
<***@highwire.org?subject=Please%20register%20me%20for%20HighWire%20Summer%20Publishers'%20Meeting%20in%20London!>*
STM Annual US Conference, April 25-27: Michiel Klein Swormink and Jennifer
Chang are representing HighWire
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>
2017 CSE Annual Meeting: John Sack is presenting on topic of Piracy, May 23
<https://t.xink.io/Tracking/Index/qKwBAMZ_AAB-KCEA0>
SSP Annual Meeting, May 31-June 2: *Visit HighWire on Booth #101A*
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>

[daemeon reiydelle]

My compliments to all of you for being adults, excessively kind, and
definitely excessively nice.


*.......*



*Daemeon C.M. ReiydelleUSA (+1) 415.501.0198London (+44) (0) 20 8144 9872*

Post by Steve Robenalt
Hi Roman,
I'm assuming you were intending your first statement to be in jest, but
it's really not that hard to startup a Cassandra cluster. The defaults are
pretty usable, so if all you want to do is set the IPs and start it up, the
cluster probably will just take care of everything else.
So I jest a little bit too. It's normally desirable to set up storage
properly for your database, and there's a few options for which you might
want to change the defaults, such as the snitch.
Still, if that means you only need to take note of of a couple of IPs and
designate them as seeds so your cluster can mostly manage itself, you can
say that's sad, but I'd say it's a small price to pay for all that you
don't have to do.
Steve

Post by Roman Naumenko
Lol yeah, why
I guess I run some ec2 instances, drop some cassandra deb packages on 'em
- the thing will figure out how to run...
Also, how would you get "initial state of the cluster" if the cluster...
is being initialized?
Or that's easy, according to the docs - just hardcode some seed IPs into
each node, lol
It's all kinda funny, but in a sad way.

Post by Jon Haddad
Why do you have to figure out what’s up w/ them by accident? You’ve
gotten all the information you need. Seeds are used to get the initial
state of the cluster and as an optimization to spread gossip faster.
That’s it.
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic
replacing seed nodes or what not.
—
Roman
The in-tree docs do not mention this anywhere, and even have some of the
https://cassandra.apache.org/doc/latest/faq/index.html?highl
ight=seed#what-are-seeds
The DataStax docs are maintained outside of the project, you’ll have to
ask them why they’re wrong or misleading.
Jon
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra
/operations/ops_replace_seed_node.html
Promote an existing node to a seed node by adding its IP address to
-seeds list and remove (demote) the IP address of the dead seed node from
the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra
/operations/ops_replace_node_t.html
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initiali
ze/initializeSingleDS.html
num_tokens: recommended value: 256
-seeds: internal IP address of each seed node
I saw also *hostnames *mentioned few times, but it just makes it even
more confusing.
—
Roman
Sure, you could use DNS. Where does it say IP addresses are a requirement?
If I understand how Cassandra nodes work, they must contain a list of
seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it
possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

--
* Steve Robenalt Software Architect, HighWire Press, Inc. *
www.highwire.org| Los Gatos, CA| Belfast, NI| Brighton, UK
<https://www.linkedin.com/company-beta/1797/>
<http://twitter.com/highwirepress>
*HighWire Summer Publishers' Meeting, London, June 12-13
STM Annual US Conference, April 25-27: Michiel Klein Swormink and Jennifer
Chang are representing HighWire
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>
2017 CSE Annual Meeting: John Sack is presenting on topic of Piracy, May 23
<https://t.xink.io/Tracking/Index/qKwBAMZ_AAB-KCEA0>
SSP Annual Meeting, May 31-June 2: *Visit HighWire on Booth #101A*
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>

[Roman Naumenko]

Service discovery (aka "note some IPs") should be part of the cluster
bootstrapping and management.

See for example how elastic is doing this. Or consul. Its pretty standard
practice these days.

--
Roman

Post by Steve Robenalt
Hi Roman,
I'm assuming you were intending your first statement to be in jest, but
it's really not that hard to startup a Cassandra cluster. The defaults are
pretty usable, so if all you want to do is set the IPs and start it up, the
cluster probably will just take care of everything else.
So I jest a little bit too. It's normally desirable to set up storage
properly for your database, and there's a few options for which you might
want to change the defaults, such as the snitch.
Still, if that means you only need to take note of of a couple of IPs and
designate them as seeds so your cluster can mostly manage itself, you can
say that's sad, but I'd say it's a small price to pay for all that you
don't have to do.
Steve

Post by Roman Naumenko
Lol yeah, why
I guess I run some ec2 instances, drop some cassandra deb packages on 'em
- the thing will figure out how to run...
Also, how would you get "initial state of the cluster" if the cluster...
is being initialized?
Or that's easy, according to the docs - just hardcode some seed IPs into
each node, lol
It's all kinda funny, but in a sad way.

Post by Jon Haddad
Why do you have to figure out what’s up w/ them by accident? You’ve
gotten all the information you need. Seeds are used to get the initial
state of the cluster and as an optimization to spread gossip faster.
That’s it.
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic
replacing seed nodes or what not.
—
Roman
The in-tree docs do not mention this anywhere, and even have some of the
https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds
The DataStax docs are maintained outside of the project, you’ll have to
ask them why they’re wrong or misleading.
Jon
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html
Promote an existing node to a seed node by adding its IP address to
-seeds list and remove (demote) the IP address of the dead seed node from
the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html
num_tokens: recommended value: 256
-seeds: internal IP address of each seed node
I saw also *hostnames *mentioned few times, but it just makes it even
more confusing.
—
Roman
Sure, you could use DNS. Where does it say IP addresses are a requirement?
If I understand how Cassandra nodes work, they must contain a list of
seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it
possible to use DNS name for seed nodes?
Thanks,
—
Roman
---------------------------------------------------------------------

--
* Steve Robenalt Software Architect, HighWire Press, Inc. *
www.highwire.org| Los Gatos, CA| Belfast, NI| Brighton, UK
<https://www.linkedin.com/company-beta/1797/>
<http://twitter.com/highwirepress>
*HighWire Summer Publishers' Meeting, London, June 12-13
STM Annual US Conference, April 25-27: Michiel Klein Swormink and Jennifer
Chang are representing HighWire
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>
2017 CSE Annual Meeting: John Sack is presenting on topic of Piracy, May 23
<https://t.xink.io/Tracking/Index/qKwBAMZ_AAB-KCEA0>
SSP Annual Meeting, May 31-June 2: *Visit HighWire on Booth #101A*
<https://t.xink.io/Tracking/Index/XaoBAMZ_AAB-KCEA0>

[Jon Haddad]

You’re free to supply your own Seed Provider. The Seed provider that comes with cassandra needs hard coded IPs, but there’s no reason why it has to be that way.

There’s a handful of ideas here: https://issues.apache.org/jira/browse/CASSANDRA-12627 <https://issues.apache.org/jira/browse/CASSANDRA-12627>

Feel free to experiment, and good luck.

Service discovery (aka "note some IPs") should be part of the cluster bootstrapping and management.
See for example how elastic is doing this. Or consul. Its pretty standard practice these days.
--
Roman
Hi Roman,
I'm assuming you were intending your first statement to be in jest, but it's really not that hard to startup a Cassandra cluster. The defaults are pretty usable, so if all you want to do is set the IPs and start it up, the cluster probably will just take care of everything else.
So I jest a little bit too. It's normally desirable to set up storage properly for your database, and there's a few options for which you might want to change the defaults, such as the snitch.
Still, if that means you only need to take note of of a couple of IPs and designate them as seeds so your cluster can mostly manage itself, you can say that's sad, but I'd say it's a small price to pay for all that you don't have to do.
Steve
Lol yeah, why
I guess I run some ec2 instances, drop some cassandra deb packages on 'em - the thing will figure out how to run...
Also, how would you get "initial state of the cluster" if the cluster... is being initialized?
Or that's easy, according to the docs - just hardcode some seed IPs into each node, lol
It's all kinda funny, but in a sad way.
Why do you have to figure out what’s up w/ them by accident? You’ve gotten all the information you need. Seeds are used to get the initial state of the cluster and as an optimization to spread gossip faster. That’s it.

Post by Roman Naumenko
Well, I guess I have to figure out what’s up with IPs/hostnames by experiment.
Information about service discovery is practically absent.
Not to mention all important details about fqdns/hostnames, automatic replacing seed nodes or what not.
—
Roman

Post by Jon Haddad
https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds <https://cassandra.apache.org/doc/latest/faq/index.html?highlight=seed#what-are-seeds>
The DataStax docs are maintained outside of the project, you’ll have to ask them why they’re wrong or misleading.
Jon

Post by Roman Naumenko
The docs mention IP addresses everywhere.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_seed_node.html>
Promote an existing node to a seed node by adding its IP address to -seeds list and remove (demote) the IP address of the dead seed node from the cassandra.yaml file for each node in the cluster.
http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html <http://docs.datastax.com/en/archived/cassandra/2.0/cassandra/operations/ops_replace_node_t.html>
Note the Address of the dead node; it is used in step 5.
http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html <http://docs.datastax.com/en/cassandra/2.1/cassandra/initialize/initializeSingleDS.html>

num_tokens: recommended value: 256
-seeds: internal IP address of each seed node

I saw also hostnames mentioned few times, but it just makes it even more confusing.
—
Roman

Sure, you could use DNS. Where does it say IP addresses are a requirement?

If I understand how Cassandra nodes work, they must contain a list of seed’s IP addressed in config file.
This requirement makes cluster setup unnecessarily complicated. Is it possible to use DNS name for seed nodes?
Thanks,
—
Roman
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