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From Michal Michalski <mich...@opera.com>
Subject Re: index_interval file size is the same after modifying 128 to 512?
Date Tue, 26 Mar 2013 08:35:03 GMT
Dean, as I can see you are satisfied with the result of increasing ii 
from 128 to 512, didn't you observed any drawbacks of this change? I 
remember you mentioned no change in Read Latency and a significant drop 
of heap size, but did you check any other metrics?

I did the opposite (512 -> 128; before we've had problems with heap 
size, now we can revert it, so I check if it makes sense) and I do not 
see almost any difference in Read Latency too, but I can see that the 
number of dropped READ messages has decreased significantly (it's 1 or 
even 2 orders of magnitude lower for the nodes I set ii = 128 comparing 
to the nodes with ii = 512; the exact value is about 0.005 / sec. 
comparing to about 0.01 - 0.2 for other nodes) and I have much less 
connection resets reported by netstat's Munin plugin. In other words, as 
I understand it - there's much less timeouts which should improve 
overall C* performance, even if I can't see it in read latency graph for 
CFs (unluckily I don't have a graph for StorageProxy latencies to easily 
check it).

To make sure about the reason of this differences and its effect on C* 
performance, I'm looking for some "references" in other people's 
experience / observations :-)

M.

W dniu 22.03.2013 17:17, Hiller, Dean pisze:
> I was just curious.  Our RAM has significantly reduced but the *Index.db files are the
same size size as before.
>
> Any ideas why this would be the case?
>
> Basically, Why is our disk size not reduced since RAM is way lower?  We are running strong
now with 512 index_interval for past 2-3 days and RAM never looked better.  We were pushing
10G before and now we are 2G slowing increasing to 8G before gc compacts the long lived stuff
which goes back down to 2G again…..very pleased with LCS in our system!!!!!
>
> Thanks,
> Dean
>


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