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The latest OpenStack Ocata releases of the Cinder, Swift and Manila storage projects focus on stability, availability and other enterprise features.
Developers working on the Cinder block storage service concentrated on bug fixes and support for active-active high availability (HA) with the OpenStack Ocata release, according to Sean McGinnis, the project technical lead (PTL) of the OpenStack Cinder block storage service and principal architect at Huawei Technologies.
Cinder is the most popular OpenStack open source storage project.
McGinnis said most of the HA work is complete, enabling a Cinder service to run for redundancy in the event a node fails or a service needs to be taken offline for an upgrade or some other reason. But he said testing still needs to be done with various back-end drivers to ensure there are no issues due to concurrent operations. McGinnis noted that the Ocata time frame was a shorter than the usual OpenStack cycle.
Also, with OpenStack Ocata, McGinnis said the Cinder team "deprecated" the consistency groups feature. He said deprecation in OpenStack means the functionality remains in the current release, but is due for removal in the next release. McGinnis said users might need to update scripts or custom programs because APIs and command lines changed, but he doesn't think the feature had wide deployment.
McGinnis said consistency groups were replaced with equivalent functionality through "generic volume groups" that allow users to logically group volumes based on their needs. The new volume grouping facilitates consistent snapshots and, in the future, will pave the way for the replication of a volume group to another back end for data protection, he said.
Other key Cinder features in the OpenStack Ocata release include support for rolling updates and micro-versions. The rolling update support means users don't need to shut down all Cinder services in order to upgrade them. Micro-versions allow an API to evolve while maintaining backward compatibility.
"The benefit for end users with micro-versions is they can write scripts and code that requests a specific version of the API and know that that version will not change as the cloud gets upgraded to later releases," McGinnis said. "Conversely, they can write code that asks for a specific version and find out whether newer functionality is available or not and fall back to older logic, if needed."
The OpenStack Foundation's April 2017 user survey showed the most popular Cinder driver continues to be the Ceph RADOS Block Device (RBD). Nearly half of the 363 respondents indicated they use Ceph RBD in production. Behind Ceph are the logical volume manager for Linux at 15% in production use, NetApp at 10%, NFS at 8% and Dell EMC at 5%.
OpenStack Swift updates
The Swift object storage service, one of the founding OpenStack projects seven years ago, is used the most for application data and backups, according to the latest OpenStack user survey. Other common data types include documents and static web content.
Updates to Swift in the OpenStack Ocata cycle included improved erasure code storage and the back-end consistency engine.
John Dickinson, the Swift PTL and director of technology at San Francisco-based SwiftStack, said additional work in the broader ecosystem is making Swift available for different use cases. He noted improvements to the way Swift works with modern hard drives and storage chassis; enterprise features, such as tiering, policy migration and encryption; and work to make Swift operate well in multicloud and hybrid cloud environments, such as Amazon Web Services and Google.
Latest OpenStack Manila release
Ben SwartzlanderOpenStack Manila PTL and architect at NetApp
The newest OpenStack storage project, the Manila shared file service, continues to see steady adoption, according to Ben Swartzlander, the Manila PTL and architect at NetApp, based in Sunnyvale, Calif. The latest OpenStack user survey showed the most popular Manila driver is the Ceph Filesystem, which 53% of the 51 respondents indicated they use. Others include NetApp at 28%; the generic Manila driver at 20%; GlusterFS at 8%; and Huawei and IBM's General Parallel File System, both at 4%.
New capabilities in Manila's OpenStack Ocata release include support for mountable snapshots, reverting a share back to a snapshot and preserving snapshots during migration. Swartzlander said the project added the cheaper option to mount snapshots directly, rather than creating shares from snapshots.
Manila's OpenStack Ocata release also added new drivers for Dell EMC VMAX, QNAP and MapR-FS, and the project removed consistency groups and replaced with them with experimental generic share groups.
"The original consistency groups feature was not flexible enough and not used at all, to our knowledge," Swartzlander said. "Users asked for a more flexible grouping construct, so we rearchitected the feature."
He said the Manila project is also working on support for Tooz to enable distributed locking in HA environments. Swartzlander said Manila is gradually adding primitives to enable deployments across multiple controller nodes for additional scalability and reliability.
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