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From Robert Coli <>
Subject Re: Defrag
Date Wed, 02 Mar 2011 23:40:15 GMT
On Wed, Mar 2, 2011 at 2:51 PM, Peter Schuller
<> wrote:
> Cassandra is about as friendly as it can be with respect to
> fragmentation. All data is written sequentially and in bulk.

That said, there can be more than one thread writing at a time, which
doesn't help fragmentation. On the plus side, "more than one" is never
more than a handful, which is relatively fragmentation-friendly.

Potential sources of simultaneous disk write :

- Memtable flushing
- SSTable compaction/anticompaction
- SSTable streaming
- Commitlog writes (which should be on a different drive from data per
best practices anyway..)


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