On Mon, Feb 3, 2014 at 12:51 AM, olek.stasiak@gmail.com <olek.stasiak@gmail.com> wrote:
We've faced very similar effect after upgrade from 1.1.7 to 2.0 (via
1.2.10). Probably after upgradesstable  (but it's only a guess,
because we noticed problem few weeks later), some rows became
tombstoned.

To be clear, you didn't run SSTableloader at all? If so, this is the hypothetical case where normal streaming operations (replacing a node? what streaming did you do?) results in data loss...

Also, CASSANDRA-6527 is a good reminder regarding the following :

https://engineering.eventbrite.com/what-version-of-cassandra-should-i-run/

=Rob