database solutions for a lot of writes
 

What are the best database solutions out there for sites that do a lot of writes? We use MySQL currently with replication which is fine for load balancing the SELECT's but is clearly useless when a master server goes down.

I don't think MySQL cluster will work for us.. what do you guys who have a lot of dynamic user-generated content use? We are more concerned about performance and availabilty than cost.

Sounds like your looking for a Active- Active cluster, i was talking to someone at internext about this same issue. I personally do not know a solution for Mysql that does this. Oracle, Sybase, MS Sql all have it but havent been able to find one for MySql yet. If you find one please share

Use the MySQL InnoDB engine?

I could be wrong, but I thought that was for high-transaction purposes.

http://mysql.com/doc/refman/5.0/en/innodb-overview.html

Easiest: Buy more (SCSI or SAS) disk. SATA, even though it's getting better, still cannot even hold a candle to SCSI (or SAS) based arrays for random writes. The difference still astounds me whenever I put one into production, it's such a difference that it almost defies logic.

Not-so-easy: Re-code application to support MySQL cluster type stuff (e.g. in-RAM tables). Must be able to survive some possible data loss

Hard: Re-code application to be "really smart" (tm) about database writes, and load balance across multiple database servers. This requires more than a little logic in the code though, both from a writes and reads standpoint.

Hardest: move to Oracle or somesuch, and scale horizontally on really expensive hardware :)

In short.. it really all lies with the application, which unfortunately is usually the hardest part to fix.

Hope it helps.

-Phil