Ivan mentions the Q and As from a Q&A session in which MySQL Cluster is mentioned – I thought I’d add my perspective here as well:

Q from Matthew: When are we likely to see disk based indexing for ndb?
Disk based indexing is planned in one of the future releases, but we can’t say when we will implement it. During the webinar, Anders pointed out that he does not see this as an important thing. I tend to agree with Anders, at least considering the current status of the storage engine. At the moment, ndb can perform an unbeatable job (in terms of HA and performance) on small transactions and simple queries and we should not consider it as a full replacement for the whole database, in general. The future versions of ndb will probably be more and more general purpose and at some point a full disk based ndb will be valuable. Please take this as my personal opinion.

Implementing disk based indexes is a fair bit of work… Certainly not this year (or early next). Sure, it’s a crucial step towards world domination… but it does have to sit in a priority queue of other steps.

Q from Malcolm: Is their any difference between MysQL Cluster and the telecoms version?
As Bertrand said, MySQL Cluster Carrier Grade is a specific version for telecom, developed closely with major equipment manufacturers. During the presentation I have highlighted some differences – such as the availability of more data nodes and so on. We will cover MySQL Cluster and MySQL Cluster Carrier Grade Edition in one of the future sessions.

It’ll be good to have a special session on the difference. The basic difference is that we’re a bit more selective about what patches go into the Carrier grade trees – and sometimes some features will go there first (when customers really need it). We will typically try to be less invasive in some areas too. Odds are though, if you’re not a telco, you don’t need it.

Q from Fabio: Any plan for MySQL Cluster for Windows?
We are considering it sometimes in the future, but no plans have been made so far.

Yes, this has been “being considered” for years. No, it’s not going to happen any time soon. Patches welcome.

Q from Owen: Is it difficult to define memory requirements for MySQL Cluster?
MySQL Cluster configuration is the most important step when you adopt this technology. We have seen several do-it-yourself configurations, running perfectly. But Cluster configuration is not straightforward and we always recommend to get some help from our Professional Services team.

Each time I patch ndb_size.pl it gets more accurate and is less outrageously wrong in some scenarios now :) It can help… although you also need to know what you’re measuring – and account for future growth.

Q from Alessandro: Is carrier grade avalaible for download?
As Bertrand said, please contact us at http://www.mysql.com/company/contact/ if you are interested in MySQL Cluster Carrier Grade for telecom customers

I beleive the plan is to publish the BK trees as well… but certainly not the supported way to run it.

There was also some talk on DRBD and shared disk clusters. Neither of these prevent against file system corruption. Also, if using a non-crash safe engine (e.g. MyISAM) when you fail over you’ll probably have to do a bunch of table checks – not exactly HA.