I finally tried the global snapshots stuff below is what I did.
I have taken data from all individual nodes from a single DC after changing the numerical part(this numerical part can have only a max value of 2147483647).
1.My individual nodes were having 12Gb odd data so after combining it was around 77 Gb of data.
2.My new ring had exact configuration in terms of number of nodes,RF and token distribution.
3.I copied all the data on all individual nodes and ran cleanup.
4.After running cleanup all the nodes had an data in range of 34Gb-38Gb .
5.The data on all the nodes was correct validated against the original ring.
6.One of the node in a DC had data close to 68Gb and running cleanup didnt triggered anything
What I can't understood by now is the
1.Is the data size correct . I have RF=3 and 6 nodes in one DC as on the other . Is it because ((77 * 3)/6
2.Why was one node having 68Gb data .
Below is the ring status
Address DC Rack Status State Load Owns Token
11.60 DC1 RC1 Up Normal 38.83 GB 8.33% 0
6.136 DC2 RC1 Up Normal 34.49 GB 8.33% 14178431955039101857246194831382806528
11.61 DC1 RC2 Up Normal 37.62 GB 8.33% 28356863910078203714492389662765613056
6.137 DC2 RC2 Up Normal 33.96 GB 8.33% 42535295865117307932921825928971026432
11.62 DC1 RC1 Up Normal 36.91 GB 8.33% 56713727820156407428984779325531226112
6.138 DC2 RC1 Up Normal 34.12 GB 8.33% 70892159775195516369780698461381853184
11.63 DC1 RC2 Up Normal 37.63 GB 8.33% 85070591730234615865843651857942052864
6.139 DC2 RC2 Up Normal 33.84 GB 8.33% 99249023685273724806639570993792679936
11.64 DC1 RC1 Up Normal 38.83 GB 8.33% 113427455640312814857969558651062452224
6.140 DC2 RC1 Up Normal 34.37 GB 8.33% 127605887595351923798765477786913079296
11.65 DC1 RC2 Up Normal 39.54 GB 8.33% 141784319550391032739561396922763706368
6.141 DC2 RC2 Up Normal 68.29 GB 8.33% 155962751505430122790891384580033478656
From: Tamar Fraenkel [email@example.com]
Sent: Wednesday, May 02, 2012 11:13 AM
Subject: Re: Taking a Cluster Wide Snapshot
I think it make's sense and would be happy if you can share the incremental snapshot scripts.
Senior Software Engineer, TOK Media
On Tue, May 1, 2012 at 11:06 AM, Shubham Srivastava
On another thought I am writing a code/script for taking a backup of all the nodes in a single DC , renaming data files with some uid and then merging them . The storage however would happen on
some storage medium nas for ex which would be in the same DC. This would help in data copying a non hefty job.
Hopefully the one single DC data(from all the nodes in this DC) should give me the complete data just in case if RF >=1 .
The next improvement would be do do the same on incremental snapshots so that once you have a baseline data all the rest would be collecting chunks of increments alone and merging it with the original global snapshot.
I have do the same on each individual DC's.
Do you guys agree?
Thanks for posting the script.
I see that the snapshot is always a full one, and if I understand correctly, it replaces the old snapshot on S3. Am I right?
Senior Software Engineer, TOK Media
On Thu, Apr 26, 2012 at 9:39 AM, Deno Vichas
here's how i'm doing in AWS land using the DataStax AMI via a nightly cron job.
you'll need pssh and s3cmd -
On 4/25/2012 11:34 PM, Shubham Srivastava wrote:
Whats the best way(or the only way) to take a cluster wide backup of Cassandra. Cant find much of the documentation on the same.
I am using a MultiDC setup with cassandra 0.8.6.
echo "making snapshots"
pssh -h prod-cassandra-nodes.txt -l ubuntu -P 'nodetool -h localhost -p 7199 clearsnapshot stocktouch'
pssh -h prod-cassandra-nodes.txt -l ubuntu -P 'nodetool -h localhost -p 7199 snapshot stocktouch'
echo "making tar balls"
pssh -h prod-cassandra-nodes.txt -l ubuntu -P -t 0 'rm `hostname`-cassandra-snapshot.tar.gz'
pssh -h prod-cassandra-nodes.txt -l ubuntu -P -t 0 'tar -zcvf `hostname`-cassandra-snapshot.tar.gz /raid0/cassandra/data/stocktouch/snapshots'
echo "coping tar balls"
pslurp -h prod-cassandra-nodes.txt -l ubuntu /home/ubuntu/*cassandra-snapshot.tar.gz .
echo "tar'ing tar balls"
tar -cvf cassandra-snapshots-all-nodes.tar 10*
echo "pushing to S3"
../s3cmd-1.1.0-beta3/s3cmd put cassandra-snapshots-all-nodes.tar s3://stocktouch-backups