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.