As many of you have noticed, PVS 7.1 has a brand new cache type called “Cache in Device RAM with Overflow on Hard Disk.” This new feature of PVS is designed to provide better performance by combining the light speed of RAM with the efficiency of hard disk storage and at the same time avoiding previous hurdles such as unexpected BSOD when using RAM cache due to the memory getting filled up. The new differencing format of the file (VHDX) also resolves the issue when caching to device HD where applications accessing printer drivers would randomly crash.
As some of you have noticed, however, target device performance has not increased dramatically in terms of speed. In fact, some folks out there with IOMeters have reported that IOPs have not improved at all with the new cache type. This is currently a known issue due to a problem turning on the RAM portion of the cache and I know for a fact that Citrix is working on fixing it in the next hotfix release for PVS 7.1. So stay excited!
The RAM portion of the this cache type is fixed in CTX140338 which is a target device hotfix.