Archive: Posts

In-VMware Host Caching – Datrium’s Appliance Specific Host Cache Versus Virtunet’s Host Cache for Any Storage.

Both Datrium and us differentiate from the rest of the storage appliance vendors in that both of us cache data to cache media in the VMware host instead of the storage appliance, which is the traditional approach.

But the similarities between Datrium’s and our ESXi host cache end there. The top three differences between Datrium DVX DiESL and our VirtuCache are:

  1. Our host side caching accelerates any storage appliance, Datrium’s works only for their own appliance;

  2. We cache writes and reads to in-VMware host cache media, Datrium caches only reads;

  3. We can cache to host RAM and SSD, Datrium can cache to SSD only.

So if you are a Datrium customer and if you are looking to apply the concept of host side caching that you have come to like from Datrium, to your other storage appliances, then you could do so with VirtuCache. We will accelerate the performance of any SAN based storage appliance no matter how old or slow, by caching all storage IO (reads and writes) to any in-host SSD (or host RAM).

We believe that caching data to in-VMware host high-speed media (Flash / RAM) is a better option than caching in the storage appliance because the cache media in our case is closer to the CPU that consumes ‘hot’ data, and hence the same high-speed media performs better in the VMware host than in the appliance. This principle applies equally to both reads and writes and hence we cache both reads and writes to in-host SSD (or RAM). Whereas Datrium decided to cache only reads to ESXi host SSD. The writes in the case of Datrium are cached to their appliance NVRAM, much like a traditional appliance. Datrium founder has these arguments to make in favor of caching writes to the appliance and NOT to in-VMware host cache media, which we patently disagree with. Our counterpoints to Datrium are on this link.

Also, if you use host RAM to cache with VirtuCache, VirtuCache powered infrastructure will be higher performing than any storage array or hyper-converged appliance (including Datrium) because no storage appliance or HCI hardware is capable of using large amounts of RAM in the storage IO path. And RAM is the highest performing storage media there is.