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Posted to user@cassandra.apache.org by Ad...@thomsonreuters.com on 2016/11/03 09:22:39 UTC
Write performance tuning
Hi All,
I need some help about the Cassandra 3 performance tuning. We are now upgrading from Cassandra 1 to Cassandra 3.7. After we've done all the development work and functional test, we found the writing performance is not good; the write time is about twice of the Cassandra 1. I want to know is this normal or we can do some tuning.
Some Information:
1. It is a six nodes cluster, two data centers, and three nodes for each datacenter. The consistency level we are using is LOCAL_QUORUM
2. Cassandra server Info
[Description: cid:image004.png@01D2306A.AA197F30]
3. Max Heap size is 12GB; new Heap size is 2GB.
4. I got the Cassandra server debug log from Cassandra server in attachment.
5. The result of cfstats of the largest table
Table: vsc_data
Space used (live): 17695995770
Space used (total): 17695995770
Space used by snapshots (total): 0
Off heap memory used (total): 19336644
SSTable Compression Ratio: 0.3265535268789067
Number of keys (estimate): 7894992
Memtable cell count: 3369173
Memtable data size: 257421448
Memtable off heap memory used: 0
Memtable switch count: 895
Local read count: 27804356
Local read latency: 2.066 ms
Local write count: 141749394
Local write latency: 0.311 ms
Pending flushes: 0
Bloom filter false positives: 10
Bloom filter false ratio: 0.00000
Bloom filter space used: 10787088
Bloom filter off heap memory used: 10786896
Index summary off heap memory used: 2032620
Compression metadata off heap memory used: 6517128
Compacted partition minimum bytes: 30
Compacted partition maximum bytes: 74975550
Compacted partition mean bytes: 6749
Average live cells per slice (last five minutes): 4.383624640522535
Maximum live cells per slice (last five minutes): 5722
Average tombstones per slice (last five minutes): 2.5042559003034777
Maximum tombstones per slice (last five minutes): 29521
Dropped Mutations: 0
6. The result of cfhistograms of the largest table
Percentile SSTables Write Latency Read Latency Partition Size Cell Count
(micros) (micros) (bytes)
50% 0.00 20.50 42.51 770 50
75% 1.00 51.01 73.46 1109 86
95% 17.00 1629.72 1629.72 29521 1916
98% 20.00 2816.16 25109.16 42510 3311
99% 24.00 4055.27 43388.63 51012 3973
Min 0.00 1.60 8.24 30 0
Max 35.00 3449259.15 4139110.98 74975550 5839588
Any clue will be appreciated, thank you very much!
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Adeline Pan
Senior Software Engineer
Thomson Reuters
Phone: 62674654
Adeline.pan@thomsonreuters.com