[TIL] Cassandra Backup Survey

January 7th, 2017

Preface

Our cassandra instance sometime got crash mess amount of data. To backup those data to another storage is task need to do.

CQLSH

First backup canssandra schema

Export entire schema of your cassandra.

cqlsh -e "DESC SCHEMA" > user_schema.cql

Or you can specific your keyspace here.

cqlsh -e "DESC SCHEMA" > user_schema.cql

Export and Import cassandra data

Export

COPY <tablename> [ ( column [, ...] ) ]
     FROM ( '<filename>' | STDIN )
     [ WITH <option>='value' [AND ...] ];

For example

cqlsh> COPY log.parts FROM STDIN;

Another example to transform output format

cqlsh> COPY log.chatlogs (ts, content, other) TO './chatlog.dat'
   ... WITH DELIMITER = '|' AND QUOTE = '''' AND ESCAPE = '''' AND NULL = '<null>';

Import

cqlsh> COPY emp (empid,deptid,last_name,first_name) FROM 'temp.csv';

Troubleshooting

  1. Cannot dump all DB because partition.
Error for (-5813055698912042437, -5769658640073958582): Failed to connect to all replicas ['10.123.456.789'] for (-5813055698912042437, -5769658640073958582), errors: ['NoHostAvailable - (\'Unable to connect to any servers\', {\'10.123.456.789\': error(None, "Tried connecting to [(\'10.123.456.789\', 9042)]. Last error: timed out")})'] (will try again later attempt 1 of 5)

Ans:

Because your cassandra has three partition, and it is in GCE. We only export one port for cqlsh remote connect. So, you could not get any data from your other two partition.

Try install cqlsh in GCE machine with pip install cqlsh.

  1. pip install cqlsh has some problem with copy.
'module' object has no attribute 'parse_options'

**Ans: **

We could not use cqlsh from pip, suggestion use cassanra’s cqlsh. Refer jira

sudo docker run -it cassandra /usr/bin/cqlsh

Refer:

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Evan

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