failover techniques

[csgno1]

Hello,

My client, for whom I am developing in AppLogic, is asking me if there is a way we can guard against data center failure by using two data centers. My questions are, is anyone currently doing this and/or are there any documents written on the topic, plus are the developers of AppLogic planning any features that would help make this sort of thing easier?

Thank you.

[csgno1]

A second question, do any of the applogic grid providers have multiple data centers? If I wanted some redundancy could I use two different grid providers?

[agathongroup]

csgno1,

We have a couple of AppLogic-based failover clients in multiple locations. One of the lynchpins for failover in multiple locations is the MYSQLR (MySQL Replication) appliance; it allows you to configure two MySQL server as a master-master setup, which means all of your (MySQL) data is in both locations at any time. Filesystems are a little trickier, though there are ways to replicate data on a realtime or semi-realtime basis. (I think there was even a recent post on this topic in this forum.)

You also asked if any providers have multiple data centers. We are able to bring a grid online in about a half dozen US and Canadian data centers, including Los Angeles, Denver, Dallas, Seattle, Washington DC, Vancouver and Toronto. Depending on your needs, we'd be happy to accommodate you in any way we could. If you're interested, either send me a private message here or email me at pcg@agathongroup.com.

Hope this helps,
Peter Green

[csgno1]

Thanks. I'll pass your info along. The client is an IT company and they will be choosing the hosting company.

[csgno1]

Thanks I'll look for that post on file system replication

[PeterNic]

csgno1,

Failover between applications in different datacenters is definitely possible with AppLogic, and made much easier than with traditional infrastructure.

One element of the solution is the ability to easily replicate your application's deployment between datacenters -- this way, if you have a new version or make changes, you can be sure you have an exact copy in the other datacenter.

Another element is a set of replication appliances we provide. MYSQLR is the first one, and it provides a replicated MySQL database, supporting master-slave, master-multislave, master-master and many other replication configurations. In addition, it makes setting up and maintaining replication really easy (single push of a button) and has mechanisms for notifying you if something goes wrong (e.g., one site gets disk full or becomes out of sync).

The simplest usage of MYSQLR is shown on the attached diagram -- a very simple AppLogic application, with one web server and one database server, plus two gateways. You run one copy of it in each datacenter and round-robin DNS between them (or use active/passive failover). You can see a few more typical configurations in the MYSQLR appliance documentation at http://doc.3tera.com/AppLogic24/CatDatabaseAppliancesMySQLR.html (MYSQLR is included with AppLogic 2.4.7+).

Similarly, we're working on a replicated NAS appliance, which will provide a near-realtime replication at a filesystem level, for unstructured files (as opposed to databases).

Another element is the replicated IP gateway, INSSLR (http://doc.3tera.com/AppLogic24/CatGatewayINSSLR.html), allows you to run active/passive instances of the application either on the same grid, or on different grids (as long as the IP address can be routed to both apps). We're also working with partners to provide global load balancing/failover solutions via DNS, as well as some advanced IP network techniques.

A good number of our global hosting partners offer multiple datacenters. Agathon -- who responded to your inquiry -- is a fine one among them; they can also help you set up the DR solution for your customer.

If you have further questions or want to discuss the DR solutions, please feel free to continue this thread.

Best regards,
-- Peter

[csgno1]

Thank you, this is very good information.

The impression I have from other posts is that NAS-R is still a long way off. I've used rsync but only for one way file mirroring and backups, are there two-way solutions with rsync or some other tool? I can be happy with one way for my current needs but am interested in the topic of two-way replication.

[PeterNic]

csgno1,

Last week, at the SCALE x7 event in Los Angeles I spoke with the folks who built GlusterFS (http://www.gluster.org/). From what I gathered, their software might be able to do the two-way replication at file level.

Also, I'll post info on NAS-R when it becomes available.

Best regards,
-- Peter

[HostDime]

I am not sure if this is allowed, but as this is related, I want to announce that we, HostDime.com, can serve you with data centers in Brazil, USA, and UK. We can build private grids in any of these locations.

[Sellers_PGS]

For one of 3tera based systems, we are using a commercial DNS load balancing service (TZO.com) on the front-end and MySQL multi-master replication on the back-end. The secret sauce here is that the application was built from the start to run Hot-Hot in two locations. For example, our high volume data transactions are inserts rather than updates, so the sites can disconnect and re-connect without having to worry about conflicting updates.

[tsuliman]

any updates on NAS-R do you guys have MSSQL-R appliance ? It would be good if you guys can add some use cases and examples of doing failover techniques and data replication on the website if i didnt miss it

[PeterNic]

tsulliman,

There is a NASR appliance in the standard catalog. There is currently no MSSQLR appliance, only MYSQLR. The data sheets for the NASR and MYSQLR appliances have typical usage examples (diagram with brief explanations)

Best regards,
- Peter