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GUI comparison, PernixData FVP vs Us – VMware Write Back Caching Software.

For the most part both our GUI and workflows are similar. This article compares, with screenshots, steps to install and configure VirtuCache and PernixData FVP.

The only differences between us and Pernix stem from the fact that we leverage VMware's own capability in the areas of clustering, license management, and logging, whereas Pernix programmed these features separately within their software. Overall these additional screens add a few clicks and pages in Pernix versus us, but again I want to emphasize that we are more similar than different, in terms of the GUI and workflow.

PernixData’s FVP vs. Virtunet – Both VMware Kernel Write Caching Software

More similar than different

Both us and PernixData differentiate from rest of the host side caching vendors in similar ways - that we are kernel mode software; both of us cache writes in addition to reads; have data protection strategies in place to prevent against data loss in case of multiple simultaneous hardware failure; do not require networking or storage to be reconfigured; and do not require agents per VM or VM per host.

This article is the first in a series of two articles that compares our software versus PernixData FVP. The second article compares (with screenshots) GUI and configuration steps for PernixData FVP and us.

Below is how we compare on important criteria.

Infinio’s Read Caching versus Virtunet’s Read+Write Caching Software

The biggest difference is that we cache reads and writes, Infinio caches only reads. Even in a read dominated workload, caching writes helps accelerate even the reads. The below article explains how this is so.

Then there are other differences as well like we assign caching policies at the datastore level with VM level overide, whereas Infinio caches at the VM level only. We cache both VM IO and VMware kernel IO whereas Infinio caches only VM IO. The implications of such differences between our two software are detailed below.

Reducing Write Latencies in CEPH Storage

CEPH is a popular open source storage software. However its write latencies are high. VirtuCache caches CEPH volumes to in-host SSDs and by doing so reduces VM level latencies considerably.

VMware’s vFlash Read Cache (VFRC) versus Virtunet’s Read+Write Caching

The biggest difference is that we cache reads and writes, VMware's VFRC caches only reads. Caching writes improves the performance of not only writes, but also of reads, and even in a read dominated workload.1

Then there are other differences as well –

  1. With VFRC, the in-host SSD has to be carved out amongst VMs and capacity manually assigned to each VMDK. Such manual assignment of cache capacity on a per VM basis is not required with VirtuCache;

  2. With VFRC, if a host fails or even during manual vmotion, VMs don't migrate unless the target hosts have adequate spare SSD capacity to honor SSD reservations of incoming VMs. We support VMware HA and DRS without any restrictions;

  3. VFRC only supports SSDs, VirtuCache supports both SSD and RAM;

  4. VMware View or Xendesktop do not support VFRC, we do;

  5. In VFRC, SSD failure results in interruption of storage IO, not so with VirtuCache.

For a complete list of differences, please review the below table with accompanying cross-references:

A Counter Intuitive Approach to Solve the Peculiar Problems of Video Storage

By not using dedupe, compression, or RAID, using slow HDDs in centralized storage, and moving SSDs to compute hosts, we arrived at low price per capacity and performance for video storage.

Here are unique requirements of video storage, some are obvious and others not so much, that inspired us to put together a different architecture than the conventional storage OEM design.

CEPH Storage is Ideally Suited for Disaster Recovery (DR) Infrastructure

CEPH storage from Virtunet has all the features of traditional iSCSI SAN with the exception that it is reasonably priced because it uses commodity servers with all off-the-shelf hardware. And so it is ideally suited for backup and DR storage which needs to be cheap above all else.

Improving Jenkins Performance

By improving storage performance, Virtucache was able to improve the performance of Jenkins based Continuous Integration process, which in turn resulted in quicker build-test cycles.

Improving Performance of Microsoft Dynamics AX ERP

Microsoft Dynamics AX transaction processing is write intensive and its reporting is read intensive, thus putting pressure on customer's existing storage infrastructure. By caching frequently used data from customer's existing storage to in-host SSDs, VirtuCache was able to reduce read and write latencies for AX running within VMware VMs.

EMC Fast Cache Storage Controller Based Caching for VNX Appliances versus VirtuCache Host Side Caching for Any SAN based Appliance

In case of FastCache or any storage appliance based caching, the SSD is more expensive than if the same SSD were bought retail. Also the SSD performs better in the host than in the storage appliance, since the SSD in the appliance is constrained by the network and controller.


EMC FastCache is SSD based caching functionality sold by EMC for their VNX appliances. It tiers frequently used data, mainly reads, to SSDs in the appliance from slower HDDs on the appliance.


VirtuCache is software sold by Virtunet (and competing with EMC's FastCache) that is installed in the VMware kernel along with a SSD in the same VMware host, and it caches frequently and recently used data, both reads and writes, to the in-host SSD from any SAN based storage appliance.

This blog article lists the differences between VirtuCache and EMC's FastCache.


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