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This page will gather various capacities that we identified as being useful for use cases. The EGI virtualized infrastructure will not be able to provide all of the capacities initially. However, given sufficient demand, they may eventually be implemented.

Id Capacity Description
1 Block Storage

Block storage can be attached to virtual instances at run time. Some cloud stacks even require the use of explicitly attached block storage to make any use of the instances at all.

The benefit of block storage over object storage is that the application within the virtual instance does not need to be aware of it. With block storage appearing to the VM as just another block device, from which an ordinary file system can be mounted, applications will be able to deal with this kind of storage transparently.

2 Object Storage

Object storage is scalable storage in which data objects can be stored. The FCTF have agreed on CDMI to be the access mechanism of choice.

Applications within virtual instances need to make explicit use of object storage in order to make use of it. This is a key difference in comparison to block storage. A potential solution to overcome this limitation is to try and mount object storage as a file system, e.g. via a FUSE driver. There are hints that such solutions exist.

3 Messaging

A messaging system can be used to decouple communication among distributed components of cloud "applications". At the same time, this capacity can be used at the infrastructure level. Messaging is a higher level service, which can be offered/used in several modes of operation:

  1. Directly within a VM, either a specific one deployed by the user or as part of a larger VM containing multiple components and services
  2. As a platform service offered by the cloud. Users could simply rely on its availability and make use of it.

Examples of this kind of system are: Amazon SQS [1]

4 CloudFormation

CloudFormation is the capacity to deploy collections of related resources.