RE: all the nost are not reacheable when running massive deletes

[Paco Trujillo]

Thanks Alain for all your answer:


-  In a few days I am going to set up a maintenance window so I can 
test again to run repairs and see what happens. Definitely I will run 'iostat 
-mx 5 100' On that time and also use the command you pointed to see why is 
consuming so much power.

-  About the client configuration, we had QUORUM because we were 
planning to have another data center last year (running in the locations of one 
of our clients) but at the end we postponed that. The configuration is still 
the same :), thanks for the indication. We used the downgrading policy because 
of the timeouts, and problems we had in the past with the network. In fact I 
have not seen in the logs for some months that the downgrading is occurring, so 
probably is good also to remove It from the configuration.

-  The secondary index in the cf is definitely a bad decision, taking 
at the beginning when I start getting familiar with Cassandra. The problem is 
the cf at this moment have a lot of data, and remodel it will cost some time, 
so we decide to postpone it. There are some queries which use this index,  
using materialized views on this cf and other related with it, will solve the 
problem. But for that, I need to update the cluster ☺

-  Good that you mention that LCS will not be a good idea, because I 
will planning to make a snapshot of that cf and restore the data in our test 
cluster to see if the LCS compaction will help. It was more a decision based on 
“I have to try something” than based on arguments ☺



From: Alain RODRIGUEZ [mailto:arodr...@gmail.com]
Sent: vrijdag 8 april 2016 12:46
To: user@cassandra.apache.org
Subject: Re: all the nost are not reacheable when running massive deletes

It looks like a complex issue that might worth having a close look at your data 
model, configurations and machines.

It is hard to help you from the mailing list. Yet here are some thoughts, some 
might be irrelevant or wrong, but some other might point you to your issue, 
hope we will get lucky there :-):

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
   1,000,000,400,030,00   98,57

Device: rrqm/s   wrqm/s r/s w/srMB/swMB/s avgrq-sz 
avgqu-sz   await  svctm  %util
sda   0,00 0,000,000,20 0,00 0,00 8,00 
0,000,00   0,00   0,00
sdb   0,00 0,000,000,00 0,00 0,00 0,00 
0,000,00   0,00   0,00
sdc   0,00 0,000,000,00 0,00 0,00 0,00 
0,000,00   0,00   0,00
sdd   0,00 0,200,000,40 0,00 0,0012,00 
0,002,50   2,50   0,10

CPU:


-  General use: 1 – 4 %

-  Worst case: 98% .It is when the problem comes, running massive 
deletes(even in a different machine which is receiving the deletes) or running 
a repair.

First, the cluster is definitely not overloaded. You are having an issue with 
some nodes from time to time. This looks like an imbalanced cluster. It can be 
due to some wide rows or bad partition key. Make sure writes are well balanced 
at any time with the partition you are using and try to spot some warnings 
about large row compactions in the logs. Yet, I don't think this is what you 
face as you then should have 2 or 3 nodes going crazy at the same time because 
of RF (2 or 3).

Also, can we have an 'iostat -mx 5 100' on when a node goes mad?
An other good troubleshooting tool would be using 
https://github.com/aragozin/jvm-tools/blob/master/sjk-core/COMMANDS.md#ttop-command.
 It would be interesting to see what Cassandra threads are consuming the CPU 
power. This is definitely something I would try on a high load node/time.


About the client, some comments, clearly unrelated to your issue, but probably 
worth it to be told:

.setConsistencyLevel(ConsistencyLevel.QUORUM))
 [...]
 .withRetryPolicy(new 
LoggingRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE))

I advice people to never do this. Basically, consistency level means: even in 
the worst case, I want to make sure that at least (RF / 2) + 1 got the read / 
write to consider it valid, if not drop the operation. If used for both writes 
& reads, this provide you a strong and 'immediate' consistency (no locks 
though, so excepted for some races). Data will always be sent to all the nodes 
in charge of the token (generally 2 or 3 nodes, depending on RF).

Then you say, if I can't have quorum, then go for one. Meaning you prefer 
availability, rather than consistency. Then, why not use one from the start as 
the consistency level? I would go for CL ONE or remove the 
'DowngradingConsistencyRetryPolicy'.

Also, I would go with 'LOCAL_ONE/QUORUM', using Local is not an issue when 
using only one DC as you do, but avoid some surprises when adding a new DC. If 
you don't change it, keep it in mind for the day you add a new DC.

Yet, this client does a probably well balanced

Re: all the nost are not reacheable when running massive deletes

[Alain RODRIGUEZ]

gt; idindividualmorph bigint,
>
> idreferencebuild bigint,
>
> isinexon boolean,
>
> isinorf boolean,
>
> max_length int,
>
> morphid bigint,
>
> position int,
>
> qualityflag int,
>
> ranking int,
>
> referencebuildlength int,
>
> snpsearchid uuid,
>
> synonymous boolean,
>
> PRIMARY KEY ((idline1, idline2, partid), id)
>
> ) WITH CLUSTERING ORDER BY (id ASC)
>
> AND bloom_filter_fp_chance = 0.01
>
> AND caching = 'KEYS_ONLY'
>
> AND comment = 'Table with the snp between lines'
>
> AND compaction = {'class':
> 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy'}
>
>AND compression = {'sstable_compression':
> 'org.apache.cassandra.io.compress.LZ4Compressor'}
>
> AND dclocal_read_repair_chance = 0.0
>
> AND default_time_to_live = 0
>
> AND gc_grace_seconds = 864000
>
> AND index_interval = 128
>
> AND memtable_flush_period_in_ms = 0
>
> AND populate_io_cache_on_flush = false
>
> AND read_repair_chance = 0.1
>
> AND replicate_on_write = true
>
> AND speculative_retry = '99.0PERCENTILE';
>
> CREATE INDEX snpsearch_morphid ON snpaware.snpsearch (morphid);
>
>
>
> Which holds a lot of data. It is normaly a cf which needs to be readed but
> sometimes updated and deleted and I think the problem is there. I wanted to
> change the compaction strategy but that means that a compaction will be
> executed and then timeouts will appear and I can not do that on the live
> cluster right now.
>
>
>
> I will try bring a snapshot of the cf to a test cluster and test the
> repair there (I can not snaphost the data from the live cluster completely
> because it does not fit in our test cluster). Following your recommendation
> I will postpone the upgrade of the cluster (but the partial repair in
> version 2.1 looks a good fit for my situation to decrease the pressure on
> the nodes when running compactions).
>
>
>
> Anyway I have ordered two new nodes, because maybe that will help. The
> problem is that adding a new node will need to run clean up in all nodes,
> the clean up implies a compaction? If the answer to this is yes, then the
> timeouts will appear again.
>
>
>
>
>
> *From:* Alain RODRIGUEZ [mailto:arodr...@gmail.com]
> *Sent:* dinsdag 5 april 2016 15:11
>
> *To:* user@cassandra.apache.org
> *Subject:* Re: all the nost are not reacheable when running massive
> deletes
>
>
>
>  Over use the cluster was one thing which I was thinking about, and I
> have requested two new nodes (anyway it was something already planned). But
> the pattern of nodes with high CPU load is only visible in 1 or two of the
> nodes, the rest are working correctly. That made me think that adding two
> new nodes maybe will not help.
>
>
>
> Well, then you could trying to replace this node as soon as you have more
> nodes available. I would use this procedure as I believe it is the most
> efficient one:
> http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_replace_node_t.html
> .
>
>
>
> Yet I believe it might not be a hardware or cluster throughput issue, and
> if it is a hardware issues you probably want to dig it as this machine is
> yours and not a virtual one. You might want to reuse it anyway.
>
>
>
> Some questions about the machine and their usage.
>
>
>
> Disk:
>
> What disk hardware and configuration do you use.
>
> iostat -mx 5 100 gives you? How is iowait?
>
> Any error in the system / kernel logs?
>
>
>
> CPU
>
> How much used are the CPUs in general / worst cases?
>
> What is the load average / max and how many cores have the cpu?
>
>
>
> RAM
>
> You are using 10GB heap and CMS right? You seems to say that GC activity
> looks ok, can you confirm?
>
> How much total RAM are the machines using?
>
>
>
> The point here is to see if we can spot the bottleneck. If there is none,
> Cassandra is probably badly configured at some point.
>
>
>
> when running “massive deletes” on one of the nodes
>
>
>
>  Run the deletes at slower at constant path sounds good and definitely I
> will try that.
>
>
>
> Are clients and queries well configured to use all the nodes evenly? Are
> deletes well balanced also? If not, balancing the usage of the nodes will
> probably alleviate things.
>
>
>
> The update of Cassandra is a good point but I am afraid that if I start
> the updates right now the timeouts problems will appear again. During an
> update compactions are executed? If it is not I think is safe to update the
> cluster.
>
>
>
&

RE: all the nost are not reacheable when running massive deletes

[Paco Trujillo]

pulate_io_cache_on_flush = false
AND read_repair_chance = 0.1
AND replicate_on_write = true
AND speculative_retry = '99.0PERCENTILE';
CREATE INDEX snpsearch_morphid ON snpaware.snpsearch (morphid);

Which holds a lot of data. It is normaly a cf which needs to be readed but 
sometimes updated and deleted and I think the problem is there. I wanted to 
change the compaction strategy but that means that a compaction will be 
executed and then timeouts will appear and I can not do that on the live 
cluster right now.

I will try bring a snapshot of the cf to a test cluster and test the repair 
there (I can not snaphost the data from the live cluster completely because it 
does not fit in our test cluster). Following your recommendation I will 
postpone the upgrade of the cluster (but the partial repair in version 2.1 
looks a good fit for my situation to decrease the pressure on the nodes when 
running compactions).

Anyway I have ordered two new nodes, because maybe that will help. The problem 
is that adding a new node will need to run clean up in all nodes, the clean up 
implies a compaction? If the answer to this is yes, then the timeouts will 
appear again.


From: Alain RODRIGUEZ [mailto:arodr...@gmail.com]
Sent: dinsdag 5 april 2016 15:11
To: user@cassandra.apache.org
Subject: Re: all the nost are not reacheable when running massive deletes

 Over use the cluster was one thing which I was thinking about, and I have 
requested two new nodes (anyway it was something already planned). But the 
pattern of nodes with high CPU load is only visible in 1 or two of the nodes, 
the rest are working correctly. That made me think that adding two new nodes 
maybe will not help.

Well, then you could trying to replace this node as soon as you have more nodes 
available. I would use this procedure as I believe it is the most efficient 
one: 
http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_replace_node_t.html.

Yet I believe it might not be a hardware or cluster throughput issue, and if it 
is a hardware issues you probably want to dig it as this machine is yours and 
not a virtual one. You might want to reuse it anyway.

Some questions about the machine and their usage.

Disk:
What disk hardware and configuration do you use.
iostat -mx 5 100 gives you? How is iowait?
Any error in the system / kernel logs?

CPU
How much used are the CPUs in general / worst cases?
What is the load average / max and how many cores have the cpu?

RAM
You are using 10GB heap and CMS right? You seems to say that GC activity looks 
ok, can you confirm?
How much total RAM are the machines using?

The point here is to see if we can spot the bottleneck. If there is none, 
Cassandra is probably badly configured at some point.

when running “massive deletes” on one of the nodes

 Run the deletes at slower at constant path sounds good and definitely I will 
try that.

Are clients and queries well configured to use all the nodes evenly? Are 
deletes well balanced also? If not, balancing the usage of the nodes will 
probably alleviate things.

The update of Cassandra is a good point but I am afraid that if I start the 
updates right now the timeouts problems will appear again. During an update 
compactions are executed? If it is not I think is safe to update the cluster.

I do not recommend you to upgrade right now indeed. Yet I would do it asap (= 
as soon as the cluster is ready and clients are compatible with the new 
version). You should always start operations with an healthy cluster or you 
might end in a worst situation. Compactions will run normally. Make sure not to 
run any streaming process (repairs / bootstrap / node removal) during the 
upgrade and while you have not yet run "nodetool upgradesstable". There is a 
lot of informations out there about upgrades.

C*heers,
---
Alain Rodriguez - al...@thelastpickle.com<mailto:al...@thelastpickle.com>
France

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com

2016-04-05 10:32 GMT+02:00 Paco Trujillo 
<f.truji...@genetwister.nl<mailto:f.truji...@genetwister.nl>>:
Hi daemeon

We have check network and it is ok, in fact the nodes are connecting between 
themselves with a dedicated network.

From: daemeon reiydelle [mailto:daeme...@gmail.com<mailto:daeme...@gmail.com>]
Sent: maandag 4 april 2016 18:42
To: user@cassandra.apache.org<mailto:user@cassandra.apache.org>
Subject: Re: all the nost are not reacheable when running massive deletes


Network issues. Could be jumbo frames not consistent or other.

sent from my mobile

sent from my mobile
Daemeon C.M. Reiydelle
USA 415.501.0198
London +44.0.20.8144.9872<tel:%2B44.0.20.8144.9872>
On Apr 4, 2016 5:34 AM, "Paco Trujillo" 
<f.truji...@genetwister.nl<mailto:f.truji...@genetwister.nl>> wrote:
Hi everyone

We are having problems with our cluster (7 nodes version 2.0.17) when running 
“massive d

RE: all the nost are not reacheable when running massive deletes

[Paco Trujillo]

Hi daemeon

We have check network and it is ok, in fact the nodes are connecting between 
themselves with a dedicated network.

From: daemeon reiydelle [mailto:daeme...@gmail.com]
Sent: maandag 4 april 2016 18:42
To: user@cassandra.apache.org
Subject: Re: all the nost are not reacheable when running massive deletes


Network issues. Could be jumbo frames not consistent or other.

sent from my mobile

sent from my mobile
Daemeon C.M. Reiydelle
USA 415.501.0198
London +44.0.20.8144.9872
On Apr 4, 2016 5:34 AM, "Paco Trujillo" 
<f.truji...@genetwister.nl<mailto:f.truji...@genetwister.nl>> wrote:
Hi everyone

We are having problems with our cluster (7 nodes version 2.0.17) when running 
“massive deletes” on one of the nodes (via cql command line). At the beginning 
everything is fine, but after a while we start getting constant 
NoHostAvailableException using the datastax driver:

Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All 
host(s) tried for query failed (tried: 
/172.31.7.243:9042<http://172.31.7.243:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.245:9042<http://172.31.7.245:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.246:9042<http://172.31.7.246:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.247:9042<http://172.31.7.247:9042>, 
/172.31.7.232:9042<http://172.31.7.232:9042>, 
/172.31.7.233:9042<http://172.31.7.233:9042>, 
/172.31.7.244:9042<http://172.31.7.244:9042> [only showing errors of first 3 
hosts, use getErrors() for more details])


All the nodes are running:

UN  172.31.7.244  152.21 GB  256 14.5%  
58abea69-e7ba-4e57-9609-24f3673a7e58  RAC1
UN  172.31.7.245  168.4 GB   256 14.5%  
bc11b4f0-cf96-4ca5-9a3e-33cc2b92a752  RAC1
UN  172.31.7.246  177.71 GB  256 13.7%  
8dc7bb3d-38f7-49b9-b8db-a622cc80346c  RAC1
UN  172.31.7.247  158.57 GB  256 14.1%  
94022081-a563-4042-81ab-75ffe4d13194  RAC1
UN  172.31.7.243  176.83 GB  256 14.6%  
0dda3410-db58-42f2-9351-068bdf68f530  RAC1
UN  172.31.7.233  159 GB 256 13.6%  
01e013fb-2f57-44fb-b3c5-fd89d705bfdd  RAC1
UN  172.31.7.232  166.05 GB  256 15.0%  4d009603-faa9-4add-b3a2-fe24ec16a7c1

but two of them have high cpu load, especially the 232 because I am running a 
lot of deletes using cqlsh in that node.

I know that deletes generate tombstones, but with 7 nodes in the cluster I do 
not think is normal that all the host are not accesible.

We have a replication factor of 3 and for the deletes I am not using any 
consistency (so it is using the default ONE).

I check the nodes which a lot of CPU (near 96%) and th gc activity remains on 
1.6% (using only 3 GB from the 10 which have assigned). But looking at the 
thread pool stats, the mutation stages pending column grows without stop, could 
be that the problem?

I cannot find the reason that originates the timeouts. I already have increased 
the timeouts, but It do not think that is a solution because the timeouts 
indicated another type of error. Anyone have a tip to try to determine where is 
the problem?

Thanks in advance

RE: all the nost are not reacheable when running massive deletes

[Paco Trujillo]

Hi Alain


-  Over use the cluster was one thing which I was thinking about, and I 
have requested two new nodes (anyway it was something already planned). But the 
pattern of nodes with high CPU load is only visible in 1 or two of the nodes, 
the rest are working correctly. That made me think that adding two new nodes 
maybe will not help.


-  Run the deletes at slower at constant path sounds good and 
definitely I will try that. Anyway I have similar errors during the weekly 
repair, even without the deletes running.



-  Our cluster is inhouse one, each machine ois only use as a Cassandra 
node.



-  Logs are quite normal, even when the timeouts start to appear on the 
client.



-  The update of Cassandra is a good point but I am afraid that if I 
start the updates right now the timeouts problems will appear again. During an 
update compactions are executed? If it is not I think is safe to update the 
cluster.

Thanks for your comments

From: Alain RODRIGUEZ [mailto:arodr...@gmail.com]
Sent: maandag 4 april 2016 18:35
To: user@cassandra.apache.org
Subject: Re: all the nost are not reacheable when running massive deletes

Hola Paco,

the mutation stages pending column grows without stop, could be that the problem

CPU (near 96%)

Yes, basically I think you are over using this cluster.

but two of them have high cpu load, especially the 232 because I am running a 
lot of deletes using cqlsh in that node.

Solutions would be to run delete at a slower & constant path, against all the 
nodes, using a balancing policy or adding capacity if all the nodes are facing 
the issue and you can't slow deletes. You should also have a look at iowait and 
steal, see if CPU are really used 100% or masking an other issue. (disk not 
answering fast enough or hardware / shared instance issue). I had some noisy 
neighbours at some point while using Cassandra on AWS.

 I cannot find the reason that originates the timeouts.

I don't see it that weird while being overusing some/all the nodes.

I already have increased the timeouts, but It do not think that is a solution 
because the timeouts indicated another type of error

Any relevant logs in Cassandra nodes (other than dropped mutations INFO)?

7 nodes version 2.0.17

Note: Be aware that this Cassandra version is quite old and no longer 
supported. Plus you might face issues that were solved already. I know that 
upgrading is not straight forward, but 2.0 --> 2.1 brings an amazing set of 
optimisations and some fixes too. You should try it out :-).

C*heers,
---
Alain Rodriguez - al...@thelastpickle.com<mailto:al...@thelastpickle.com>
France

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com


2016-04-04 14:33 GMT+02:00 Paco Trujillo 
<f.truji...@genetwister.nl<mailto:f.truji...@genetwister.nl>>:
Hi everyone

We are having problems with our cluster (7 nodes version 2.0.17) when running 
“massive deletes” on one of the nodes (via cql command line). At the beginning 
everything is fine, but after a while we start getting constant 
NoHostAvailableException using the datastax driver:

Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All 
host(s) tried for query failed (tried: 
/172.31.7.243:9042<http://172.31.7.243:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.245:9042<http://172.31.7.245:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.246:9042<http://172.31.7.246:9042> 
(com.datastax.driver.core.exceptions.DriverException: Timeout while trying to 
acquire available connection (you may want to increase the driver number of 
per-host connections)), /172.31.7.247:9042<http://172.31.7.247:9042>, 
/172.31.7.232:9042<http://172.31.7.232:9042>, 
/172.31.7.233:9042<http://172.31.7.233:9042>, 
/172.31.7.244:9042<http://172.31.7.244:9042> [only showing errors of first 3 
hosts, use getErrors() for more details])


All the nodes are running:

UN  172.31.7.244  152.21 GB  256 14.5%  
58abea69-e7ba-4e57-9609-24f3673a7e58  RAC1
UN  172.31.7.245  168.4 GB   256 14.5%  
bc11b4f0-cf96-4ca5-9a3e-33cc2b92a752  RAC1
UN  172.31.7.246  177.71 GB  256 13.7%  
8dc7bb3d-38f7-49b9-b8db-a622cc80346c  RAC1
UN  172.31.7.247  158.57 GB  256 14.1%  
94022081-a563-4042-81ab-75ffe4d13194  RAC1
UN  172.31.7.243  176.83 GB  256 14.6%  
0dda3410-db58-42f2-9351-068bdf68f530  RAC1
UN  172.31.7.233  159 GB 256 13.6%  
01e013fb-2f57-44fb-b3c5-fd89d705bfdd  RAC1
UN  172.31.7.232  166.05 GB  256 15.0%  4d009603-faa9-4add-b3a2-fe24ec16a7c1

but two of them have high cpu load, especially the 232 because I am runni

Re: all the nost are not reacheable when running massive deletes

[daemeon reiydelle]

Network issues. Could be jumbo frames not consistent or other.

sent from my mobile

sent from my mobile
Daemeon C.M. Reiydelle
USA 415.501.0198
London +44.0.20.8144.9872
On Apr 4, 2016 5:34 AM, "Paco Trujillo"  wrote:

> Hi everyone
>
>
>
> We are having problems with our cluster (7 nodes version 2.0.17) when
> running “massive deletes” on one of the nodes (via cql command line). At
> the beginning everything is fine, but after a while we start getting
> constant NoHostAvailableException using the datastax driver:
>
>
>
> Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException:
> All host(s) tried for query failed (tried: /172.31.7.243:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.245:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.246:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.247:9042, /172.31.7.232:9042, /
> 172.31.7.233:9042, /172.31.7.244:9042 [only showing errors of first 3
> hosts, use getErrors() for more details])
>
>
>
>
>
> All the nodes are running:
>
>
>
> UN  172.31.7.244  152.21 GB  256 14.5%
> 58abea69-e7ba-4e57-9609-24f3673a7e58  RAC1
>
> UN  172.31.7.245  168.4 GB   256 14.5%
> bc11b4f0-cf96-4ca5-9a3e-33cc2b92a752  RAC1
>
> UN  172.31.7.246  177.71 GB  256 13.7%
> 8dc7bb3d-38f7-49b9-b8db-a622cc80346c  RAC1
>
> UN  172.31.7.247  158.57 GB  256 14.1%
> 94022081-a563-4042-81ab-75ffe4d13194  RAC1
>
> UN  172.31.7.243  176.83 GB  256 14.6%
> 0dda3410-db58-42f2-9351-068bdf68f530  RAC1
>
> UN  172.31.7.233  159 GB 256 13.6%
> 01e013fb-2f57-44fb-b3c5-fd89d705bfdd  RAC1
>
> UN  172.31.7.232  166.05 GB  256 15.0%
> 4d009603-faa9-4add-b3a2-fe24ec16a7c1
>
>
>
> but two of them have high cpu load, especially the 232 because I am
> running a lot of deletes using cqlsh in that node.
>
>
>
> I know that deletes generate tombstones, but with 7 nodes in the cluster I
> do not think is normal that all the host are not accesible.
>
>
>
> We have a replication factor of 3 and for the deletes I am not using any
> consistency (so it is using the default ONE).
>
>
>
> I check the nodes which a lot of CPU (near 96%) and th gc activity remains
> on 1.6% (using only 3 GB from the 10 which have assigned). But looking at
> the thread pool stats, the mutation stages pending column grows without
> stop, could be that the problem?
>
>
>
> I cannot find the reason that originates the timeouts. I already have
> increased the timeouts, but It do not think that is a solution because the
> timeouts indicated another type of error. Anyone have a tip to try to
> determine where is the problem?
>
>
>
> Thanks in advance
>

Re: all the nost are not reacheable when running massive deletes

[Alain RODRIGUEZ]

Hola Paco,


> the mutation stages pending column grows without stop, could be that the
> problem



> CPU (near 96%)
>

Yes, basically I think you are over using this cluster.

but two of them have high cpu load, especially the 232 because I am running
> a lot of deletes using cqlsh in that node.
>

Solutions would be to run delete at a slower & constant path, against all
the nodes, using a balancing policy or adding capacity if all the nodes are
facing the issue and you can't slow deletes. You should also have a look at
iowait and steal, see if CPU are really used 100% or masking an other
issue. (disk not answering fast enough or hardware / shared instance
issue). I had some noisy neighbours at some point while using Cassandra on
AWS.

 I cannot find the reason that originates the timeouts.


I don't see it that weird while being overusing some/all the nodes.

I already have increased the timeouts, but It do not think that is a
> solution because the timeouts indicated another type of error


Any relevant logs in Cassandra nodes (other than dropped mutations INFO)?

7 nodes version 2.0.17


Note: Be aware that this Cassandra version is quite old and no longer
supported. Plus you might face issues that were solved already. I know that
upgrading is not straight forward, but 2.0 --> 2.1 brings an amazing set of
optimisations and some fixes too. You should try it out :-).

C*heers,
---
Alain Rodriguez - al...@thelastpickle.com
France

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com


2016-04-04 14:33 GMT+02:00 Paco Trujillo :

> Hi everyone
>
>
>
> We are having problems with our cluster (7 nodes version 2.0.17) when
> running “massive deletes” on one of the nodes (via cql command line). At
> the beginning everything is fine, but after a while we start getting
> constant NoHostAvailableException using the datastax driver:
>
>
>
> Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException:
> All host(s) tried for query failed (tried: /172.31.7.243:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.245:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.246:9042
> (com.datastax.driver.core.exceptions.DriverException: Timeout while trying
> to acquire available connection (you may want to increase the driver number
> of per-host connections)), /172.31.7.247:9042, /172.31.7.232:9042, /
> 172.31.7.233:9042, /172.31.7.244:9042 [only showing errors of first 3
> hosts, use getErrors() for more details])
>
>
>
>
>
> All the nodes are running:
>
>
>
> UN  172.31.7.244  152.21 GB  256 14.5%
> 58abea69-e7ba-4e57-9609-24f3673a7e58  RAC1
>
> UN  172.31.7.245  168.4 GB   256 14.5%
> bc11b4f0-cf96-4ca5-9a3e-33cc2b92a752  RAC1
>
> UN  172.31.7.246  177.71 GB  256 13.7%
> 8dc7bb3d-38f7-49b9-b8db-a622cc80346c  RAC1
>
> UN  172.31.7.247  158.57 GB  256 14.1%
> 94022081-a563-4042-81ab-75ffe4d13194  RAC1
>
> UN  172.31.7.243  176.83 GB  256 14.6%
> 0dda3410-db58-42f2-9351-068bdf68f530  RAC1
>
> UN  172.31.7.233  159 GB 256 13.6%
> 01e013fb-2f57-44fb-b3c5-fd89d705bfdd  RAC1
>
> UN  172.31.7.232  166.05 GB  256 15.0%
> 4d009603-faa9-4add-b3a2-fe24ec16a7c1
>
>
>
> but two of them have high cpu load, especially the 232 because I am
> running a lot of deletes using cqlsh in that node.
>
>
>
> I know that deletes generate tombstones, but with 7 nodes in the cluster I
> do not think is normal that all the host are not accesible.
>
>
>
> We have a replication factor of 3 and for the deletes I am not using any
> consistency (so it is using the default ONE).
>
>
>
> I check the nodes which a lot of CPU (near 96%) and th gc activity remains
> on 1.6% (using only 3 GB from the 10 which have assigned). But looking at
> the thread pool stats, the mutation stages pending column grows without
> stop, could be that the problem?
>
>
>
> I cannot find the reason that originates the timeouts. I already have
> increased the timeouts, but It do not think that is a solution because the
> timeouts indicated another type of error. Anyone have a tip to try to
> determine where is the problem?
>
>
>
> Thanks in advance
>