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.
Virtunet's services and software helped Klickitat Valley Health (KVH) migrate CPSI EMR software from physical hardware to virtual. Our quote for P2V and enterprise wide hardware refresh for KVH was comparable to the quote from CPSI for just the CPSI HIS hardware upgrade.
Virtunet Write-Back Caching Improves the Performance of EMC VNX Appliance Without Requiring Any Appliance or SAN Upgrade
EMC’s VNX appliances have 3 shortcomings that VirtuCache fixes without touching the SAN and Appliance,
- They are expensive in terms of $/IOPS
- Even the high-end VNX 7500 can accommodate only 2TB of SSDs per appliance
- SSDs in the VNX that are used for tiering data from HDDs do not cache writes, hence writes are not accelerated
There are two ways to improve the performance of VNX. One is to install EMC’s FastCache SSDs in the appliance, the other is to use VirtuCache host side caching software to cache data from VNX to in-host SSDs.