vGPU is new functionality in VMware vSphere 6.0 where a physical GPU within a ESXi host can be shared across multiple VMs. vGPUs help virtualize physical GPU workstations that are used for mapping, mathematical modeling, CAD, CAM, and gaming applications.
These GPU reliant applications are storage IO intensive, since GPUs are used in situations where large computations are rapidly performed on large datasets. So it helps if this dataset is cached locally to in-VMware host high speed media instead of being retrieved from backend storage all the time. This is what VirtuCache host side caching software does. Caching data closer to the GPU results in quicker completion times for GPU assisted operations.
Creation Museum in Kentucky, USA is a museum about Bible history and creationism. Their storage needs were typical of a museum, requiring large amounts of storage for digital multimedia content related to the various exhibits at the museum.
They were looking for the below list of features from their new storage:
The ability to sustain a loss of any one component – server, HDD, SSD, NIC card, software instance etc;
The ability for this storage to interface with VMware over iSCSI;
They wanted to reuse their HP and SuperMicro servers, each of these servers was of a different vintage and configuration;
Ability to quickly search and present content that was stored on their fileserver and content management system;
It needed to be considerably low cost, especially since they already had server hardware that had all the Hard Drives and SSDs to meet their raw storage needs;
End users of these virtual desktops complained about slow boot times, Windows cursor and start button freezing and generally slow response times from the virtual desktops at various times during the day.
VirtuCache was deployed on each of the physical hosts with Seagate SATA SSDs. VirtuCache was configured to cache LUNs on their HP EVA and Xiotech appliances to a single 480 GB Seagate 600 Pro SATA SSDs installed in each of their ESXi hosts.
The chart below shows maximum latencies before and after VirtuCache for each of the VMs on the host for two consecutive Mondays. Performance data for the ESXi host shown in this graph is a representative example of the extent to which performance of each host in the cluster was improved.
By using VirtuCache with a single 480 GB Seagate enterprise SATA SSD, peak VM level latencies were reduced by a fourth or less. We ensured that maximum VM latency at all times remained under 20 milliseconds.
CEPH is fast becoming the most popular open source storage software. However it's one drawback is high latency. Host side caching software installed in VMware hosts which can cache 'hot' data from CEPH volumes to in-VMware host SSD or RAM can be used to overcome this deficiency in CEPH. We believe that this use case for host side caching software will allow CEPH to be used for latency sensitive on-premise situations.
Pros of CEPH storage.
CEPH storage software can be installed on any commodity servers. It clusters servers together and presents this cluster of servers as an iSCSI or NAS appliance. You can build CEPH storage with any server, SSD, HDD, NIC, essentially any server or server part. There is no vendor lock-in for hardware. As a result, hardware costs are low. If you want to scale up storage capacity, you can keep adding servers to this cluster, with storage capacity and performance scaling linearly as you add servers. You manage this cluster, however large, with a single GUI. All in all, it offers better reliability and deployment flexibility at a lower cost than big brand storage appliances.
One drawback of CEPH.
The one drawback with CEPH is that write latencies are high even if one uses SSDs. By deploying VirtuCache which caches hot data to in-host SSDs, we are able to get All-Flash array like latencies for CEPH storage built using slow SATA hard drives.