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From aaron morton <>
Subject Re: Removal of old data files
Date Thu, 25 Aug 2011 22:13:11 GMT
If cassandra does not have enough disk space to create a new file it will provoke a JVM GC
which should result in compacted SStables that are no longer needed been deleted. Otherwise
they are deleted at some time in the future.

Compacted SSTables have a file written out with a "compacted" extension. 

Do you see compacted sstables in the data directory?


Aaron Morton
Freelance Cassandra Developer

On 26/08/2011, at 2:29 AM, yuki watanabe wrote:

> We are using Cassandra 0.8.0 with 8 node ring and only one CF.
> Every column has TTL of 86400 (24 hours). we also set 'GC grace second' to 43200
> (12 hours).  We have to store massive amount of data for one day now and eventually for
five days if we get more disk space.  
> Even for one day, we do run out disk space in a busy day.
> We run nodetool compact command at night or as necessary then we run GC from jconsole.
We observed that  GC did remove files but not necessarily oldest ones.
> Data files from more than 36 hours ago and quite often three days ago are still there.
> Does this behavior expected or we need adjust some other parameters?
> Yuki Watanabe

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