Monday, November 7, 2011

CEPH in Ubuntu 12.04 Precise Pangolin

While at UDS (the Ubuntu Developer Summit), I attended a very interesting session on CEPH. I hadn't even heard of CEPH a week ago but I have to say that I'm impressed.

If you haven't heard of CEPH, let me give you some background:

CEPH is a distributed network storage system originally created by the folks at DreamHost. At it's most basic, CEPH stores small blocks (default 4MB) across a cluster of unreliable nodes. This is common in many modern NoSQL stores these days: no "master node" or single point of failure, easy to add more nodes, replication of data across different nodes.

On top of this basic capability, CEPH adds an S3-compatible object store and an EBS-style block device store.

The distributed block storage support has great potential.  Coming up in Ubuntu 12.04 Precise Pangolin, the block storage driver will be integrated into the kernel and also integrated into KVM.  This provides an impressive capability to run virtual machines with CEPH blockstore root devices, offering resilient storage and snapshot support for home-grown clouds. OpenStack has supported CEPH block stores since the Cactus release.  Ubuntu 12.04 Precise Pangolin will ship with OpenStack Essex which will have the latest CEPH block device storage.

For more information on CEPH, take a look at their website:


Thursday, November 3, 2011

What's New for ARM

David Brash, Architecture Program Manager at ARM, gave a presentation at the Ubuntu Developer Summit for Ubuntu 12.04 Precise Pangolin on the future of the ARM processor core.

The big highlight is the ARM v8 core, announced 27-Oct-2011. This a a new core from ARM adding 64 bit capability (AArch64) that is compatible with the existing 32 bit cores (AArch32). The focus of the new core is "power, performance, area, partnership". The core maintains the low power heritage of ARM and maintains the momentum of the ARM v7. The ARM v8 core is too new to be supported by Ubuntu 12.04 Precise Pangolin but expect full support very soon in the Linux kernel.

Another impressive update is the release of the ARM A7 and A15 processors. These are 32-bit v7 cores with 64-bit memory addressing. This allows 1TB of physical address space. The A7 is the most exciting to me. It is touted as "probably the most efficient core from ARM". It halves the performance of the A8 but reduces the power consumption by 6 times. This core should run the kernel in Precise Pangolin but without the advantage of the higher memory addressing.

ARM predicts that a $500 phone today will be available for $100 in a few years. The A7 is targeted at these low end smartphones.

The A7, A15 release also introduces a new concept called big-LITTLE. To meet demands for high performance and low power consumption, big-LITTLE puts an A7 and A15 onto the same die. When the phone is idle, code runs on the A7. When more performance is required, the running software seamlessly migrates to the A15. This combination gives the best of both worlds and ARM claims "up to 70% energy savings on common workloads."

It will be very interesting to see what devices are enabled by these new advancements.