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From Maki Watanabe <watanabe.m...@gmail.com>
Subject Re: Interpreting the output of cfhistograms
Date Tue, 26 Jul 2011 00:33:52 GMT
Offset represent different "units" for each columns.
On SSTables columns, you can see following histgrams:

20	4291637
24	28680590
29	3876198	

It means your 4291637 read operations required 20 SStables to read,
28680590 ops required 24, so on.
In Write/Read latency columns, Offset represents micro seconds.
3711340 read operations completed
in 2 ms.
Most of your row is between 925 ~ 1331 bytes.
Most of your row has 925 ~ 1331 columns.

maki


2011/7/26 Aishwarya Venkataraman <cyberaishu@gmail.com>
>
> Hello,
>
> I need help understanding the output of cfhistograms option provided as part of nodetool.
> When I run cfhistograms on one node of a 3 node cluster, I get the following :
>
> Offset SSTables Write Latency Read Latency Row Size Column Count
> 1 0 0 458457 0 0
> 2 0 0 3711340 0 0
> 3 0 0 12159992 0 0
> 4 0 0 14350840 0 0
> 5 0 0 7866204 0 0
> 6 0 0 3427977 0 0
> 7 0 0 2407296 0 0
> 8 0 0 2516075 0 0
> 10 0 0 5392567 0 0
> 12 0 0 4239979 0 0
> 14 0 0 2415529 0 0
> 17 0 0 1406153 0 0
> 20 4291637 0 380625 0 0
> 24 28680590 0 191431 0 0
> 29 3876198 0 141841 0 0
> 35 0 0 57855 0 0
> 42 0 0 15403 0 0
> 50 0 0 4291 0 0
> 60 0 0 2118 0 0
> 72 0 0 1096 0 0
> 86 0 0 662 0 0
> 179 0 0 115 173 173
> 215 0 0 70 35 35
> 258 0 0 48 0 0
> 310 0 0 41 404 404
> 372 0 0 37 0 0
> 446 0 0 22 975 975
> 770 0 0 12 3668 3668
> 924 0 0 4 10142 10142
> 1331 0 0 4 256983543 256983543
> What do these numbers mean ? How can I interpret the above data ? I found some explanation
here http://narendrasharma.blogspot.com/2011/04/cassandra-07x-understanding-output-of.html,
but I did no understand this completely.
>
> Thanks,
> Aishwarya

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