We are using Redis as well. The C code is small, compilable anywhere, and has very small memory footprint when started fresh. Redis has replaced Sphinx as our

We are using Redis as well. The C code is small, compilable anywhere, and has very small memory footprint when started fresh. Redis has replaced Sphinx as our tag indexer (thanks to its ordered sort) for more than 2 months now. It has never been down. Backup procedure is the same as our MySQL's, tgz the .rdb file to S3 daily.