NAS and SAN on AWS

Network Attached Storage (NAS) file level storage. Storage Area Network (SAN) block level storage.  NAS lends itself to quickly provisioning an exported NFS file system or CIFS share to a user backed by a thinly provisioned physical file system. SANs typically use iSCSI.  AWS does not offer native shared / clustered disk that on premise NAS and SAN offerings. Here are some options for running NAS and SAN environments in AWS:

• SAN: Zadara (also provides NFS support in addition to iSCSI). https://aws.amazon.com/marketplace/pp/B00824G9TW/ref=srh_res_product_title?ie=UTF8&sr=0-2&qid=1396040202362. Zadara is a solution that runs in an AWS Direct Connect location. 
• NAS : SoftNAS (https://aws.amazon.com/marketplace/pp/B00EQE493U) offers NFS, CIFS, and iSCSI (even though NAS in name) mount points. Pacemaker is one solution that exposes a number of EBS volumes, as a NFS mount, to an EC2 instance using EC2.   GlusterFS is another NFS solution that can be run on AWS.  This is now Red Hat Storage : http://talkincloud.com/cloud-storage/red-hat-storage-test-drives-planned-aws.   This is the second generation of highly scalable NAS software coming from Red Hat’s 2011 acquisition of Gluster.  As part of the announcement, Red Hat launched a Red Hat Storage AWS Test Drive to help enterprise customers get started with Red Hat Storage on AWS.  NetApp also offers a solution similar to Zadara (runs in AWS Direct Connect facility : http://www.netapp.com/uk/solutions/cloud/amazon-web-services.aspx 

Here is a good session from reInvent in 2013 (keep in mind this information has changed since over a year old) : http://www.slideshare.net/AmazonWebServices/nfs-and-cifs-options-for-aws-stg401-aws-reinvent-2013

https://www.youtube.com/watch?v=xbuiIwEOCAs

Of course, S3 can always be used but this will require changes to the application or use an emulation software (s3fs) to make S3 look like block/file level storage. 

Oracle RAC on AWS

Oracle Real Application Clusters (RAC) is not natively supported on AWS. The word natively is used because it is possible to run Oracle RAC in an AWS Direct Connect facility http://aws.amazon.com/directconnect/.

There are a number of options when migrating an Oracle RAC database to AWS.  The option you use depends upon the reason RAC is being used.  For HA and fail over, AWS offers multi-AZ capabilities which can provide the same level of service.  For very large databases that require high transaction through put that can not be achieved on a single instance database, Direct Connect would be the solution.  Details on these options are as follows:
1. RDS with multi-AZ :  Oracle RDS is the managed database service from AWS.  Oracle RDS has builtin multi-AZ capabilities.  Because RDS is a managed service, AWS takes care of installation, configuration and management of the secondary database, the replication between AZs, and the fail over and fail back of the database instance.
2. EC2 with multi-AZ :  Running on EC2 requires the customer or partner to install, configure, manage, and take care of the replication.    Oracle Data Guard or GoldenGate can be used for replication.
3. Direct Connect : The AWS partner Datapipe runs RAC in a managed service model using Direct Connect.

Note: Remember that AWS RDS only supports databases up to 6 TB in size. Note this number changed to 6 TB in June 2015 after being 2 TB. https://aws.amazon.com/about-aws/whats-new/2015/06/amazon-rds-increases-storage-limits-to-6TB-for-piops-and-gp2/. Check the whats new web page for any updates related to Oracle on RDS.

Note:  The reason Oracle Real Application Clusters (RAC) is not supported on AWS is:
1. Multicast is not supported on the AWS network. An overlay network is possible on AWS: http://cloudconclave.blogspot.com/2013/06/overlay-networks-on-aws.html
2. AWS EBS is not a shared disk / clustered file system.
So, even if you use a solution such as Amazon EFS, GlusterFS, Zadara, SoftNAS, or custom NFS for shared disk you can not use RAC on AWS as you need multicast support.  More on Amazon Elastic File System (EFS): https://aws.amazon.com/blogs/aws/amazon-elastic-file-system-shared-file-storage-for-amazon-ec2/ 

AWS shared disk options

Here the four options most often discussed when considering NAS/shared disk/storage on AWS:

1. S3 : Sometimes NAS isn't the right solution to the problem; it's just something that's relatively easy to implement.
2. GlusterFS, Lustre, openAFS : implementation of a distributed filesystem (GlusterFS, Lustre, openAFS, etc).  Write performance can be below writing to EBS.
3. S3-back 'filesystem' : Use a S3-backed "filesystem" (such as s3fs or Danilo's yas3fs), which is definitely easier to implement. However, write performance could become an issue.
4. NFS : You could just run NFS on another EC2 instances. However, this will not provide the fault tolerance and scalability that is built into a solution such as GlusterFS, or a solution such a Zadara. With Zadara you can have a central repository/shared file system in a NFS mount that will be accesible from EC2 machines.  You can mount Zadara from EC2 via NFS or iSCSI.
5. Of course, when you are running an Oracle database you will probably not use one of these options.  This would be like putting your on premise Oracle database storage on NFS.