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Editor to share with you the example analysis of Ceph and OpenStack, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

6.1the status of Ceph in OpenStack

For an IaaS system, the part related to storage is mainly block storage service module, object storage service module, image management module and computing service module. Specifically for OpenStack, it corresponds to four projects of Cinder, Swift, Glance and Nova [1].

In the block storage services section, Ceph is currently the default storage backend for Cinder projects. As mentioned earlier, Red Hat has also used its influence in the KVM/QEMU community to integrate RBD drivers directly into QEMU. In this way, the performance of virtual machine access to block devices based on RBD implementation will be optimized.

In the part of object storage, Swift is the object storage implementation scheme that comes with OpenStack. But Ceph has also become the strongest competitor to Swift. Currently, Swift is also considering using Ceph as its storage backend. The story about Ceph and Swift will be unfolded in detail in Section 6.2.

In the image management section, Glance already supports caching Ceph as its own local image file.

In the computing services section, United Stack is currently promoting Ceph FS as the local file system of the Nova compute node.

Overall, Ceph is actually the most popular open source storage solution in the OpenStack ecosystem. This can be confirmed by the author's personal experience on OpenStack 2013 HongKong Summit. At present, enterprise IT leading vendors represented by HP, Dell, Intel, and a number of emerging OpenStack community vendors represented by Mirantis, eNovance, United Stack, all regard Ceph as the important and even the preferred open source storage solution.

The author believes that the reason why Ceph has quickly gained attention in the OpenStack community after many years of tepid birth should be related to its ability to support unified storage, in addition to other obvious advantages. This feature is exactly what the OpenStack community needs.

One of the principles of OpenStack project design is flexibility and extensibility. At the same time, the background of each of its member projects is also different. This leads to differences in the choices taken by each project when it comes to storage systems. However, this situation is bound to lead to certain challenges to the deployment and operation and maintenance of OpenStack. Especially for some small-scale OpenStack deployment instances, if block storage, object storage, image caching, computing node local storage and other modules adopt three or four different back-end solutions, on the one hand, the deployment is very troublesome, on the other hand, the follow-up work of operation and maintenance personnel is also very cumbersome. In this case, if you can use Ceph as a unified storage back-end, it can effectively alleviate this problem. Of course, this is just a straightforward statement of the author. Any technology choice must have its complex reasons, and the information here is for reference only.

6.2 Ceph and Swift: stories that cannot but be told, comparisons that cannot but be made

First of all, a brief introduction to the context of the Swift project, so that we can better understand the characteristics of the project and the reasons behind it. The information about Swift here is mainly quoted from [2].

Swift originated in 2008 as a back-end system developed internally by Rackspace to support its public cloud object storage business. At that time, Amazon's S3 service was already popular, so Rackspace decided to develop Swift in response to provide the corresponding business. It is for this reason that the design goal of Swift is very pure, that is, an excellent object storage system comparable to S3. Other requirements are superfluous and therefore are not considered by Swift developers at all.

The development of Swift took about a year and was successfully launched in Rackspace. Since then, the OpenStack project was officially released in 2010. Rackspace contributed Swift, while NASA contributed Nova, both of which became the first two projects of OpenStack. Since then, a number of core members of the Swift development team have started their own businesses and established SwiftStack, which is still active in the relevant communities.

Thus it can be seen that Swift is a typical open source project originated within the company as a formal product development. From this point of view, Swift and "academic style" Ceph can be said to be very different. It is for this reason that Swift has gained a unique advantage: there is no shortage of startup users, and there are cases of large-scale deployment applications in the production environment from the very beginning. In fact, the relative maturity and the large number of application cases in the web scenario is still an advantage repeatedly emphasized by the Swift community.

Technically speaking, the characteristic of Swift is that the design goal is clear, that is, to be a pure object storage system, so the unified storage feature emphasized by Ceph will not be considered. At the same time, in order to facilitate integration with other projects and applications, Swift chose Python language for development.

In contrast, Ceph considers object storage, block storage and file system storage capabilities at the same time, and the scenario that is most widely used in OpenStack is actually block storage. At the same time, when choosing a development language, Ceph probably mainly considers the performance factors, so it chooses the C++ language. The fact that it can be used in block storage scenarios also partly confirms its excellent performance.

Thus it can be seen that the difference between Ceph and Swift is essentially caused by its background and application goal. It is not very fair to compare the two and judge them technically.

In fact, as two excellent representatives of open source distributed storage systems, Ceph and Swift have a lot in common in their design and features:

First of all, both of them emphasize good scalability, so they both adopt the structure without central point. It's just that Swift has a metadata server in its architecture, which solves its reliability and performance concerns as much as possible through multi-node expansion.

Second, both can provide configurable high reliability. In both clusters, the number of backups of data can be chosen, and three backups are also used in common production environments.

Third, both emphasize automated cluster management. Swift also introduces automated cluster maintenance capabilities.

Thus it can be seen that it is unreasonable and meaningless to simply emphasize that one of the two is better.

Of course, in practical use, after all, it is still necessary to choose the scheme. Combined with the point of view in [3], the author thinks that the appropriate choice may be as follows:

* if you need a pure object storage system, choose Swift

* if you need a pure block storage system, you can only choose Ceph

* if it is a small-scale OpenStack deployment scheme that wants to control the complexity of the system, select Ceph

* if it is a large-scale system, block storage and object storage have larger business requirements respectively, you can consider separating the two, using Ceph and Swift respectively.

The above is all the content of this article "sample Analysis of Ceph and OpenStack". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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