The biggest problems I see so far are:
1) not a lot of reported users, at least that I could find, although it's been kept as a feature by VMware since it was announced so there has to be quite a few. However, I didn't find lots of operational blogs, just feature announcement types.
2) more rigid implementation steps compared to Pernix FVP, which takes some reading to figure out
Biggest differences with Pernix FVP apart from the obvious:
- Instead of enabling per cluster, you have to enable it per disk on the VMs, and have to choose the block size. This means you have to use something like vSCSIstats to determine your workload, and then you will only be able to accelerate the block sizes that match, which is never 100% of storage i/o. You can change the block size of a running VM; this can be enabled/disabled while the VM is running as well.
- Implementing this requires VMs to be running HW v10 – I know lots of admins that don't religiously update their VM hardware after an upgrade, so this should be called out.
- There have been no updates in functionality since the v1.0 release in vSphere 5.5. Good news is VMware continues supporting it, and the SSD model I'm interested in is listed in the HCL for 6.5 http://www.vmware.com/resources/compatibility/detail.php?deviceCategory=vfrc&productid=36248&deviceCategory=vfrc&details=1&releases=273&deviceTypes=18&partner=454&page=1&display_interval=10&sortColumn=Partner&sortOrder=Asc
Known KB’s
There are two known issues, and they are easily avoidable as patches were released already, so just make sure you are running latest before enabling
https://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=2114498&sliceId=1&docTypeID=DT_KB_1_1&dialogID=381661788&stateId=0%200%20381669816
https://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=2072392&sliceId=1&docTypeID=DT_KB_1_1&dialogID=381647699&stateId=0%200%20381651933
Documentation
http://pubs.vmware.com/vsphere-65/index.jsp#com.vmware.vsphere.storage.doc/GUID-07ADB946-2337-4642-B660-34212F237E71.html
http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-vsphere-flash-read-cache-faq.pdf << particularly useful
http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-vfrc-performance-vsphere55-white-paper.pdf << cool read
Blog posts
http://cormachogan.com/2014/02/14/a-closer-look-at-vsphere-flash-read-cache-vfrc/
http://nolabnoparty.com/en/vmware-vflash-read-cache-setup/
http://everything-virtual.com/vmware-study-guides/vcap-dca-study-guide/configure-and-manage-vsphere-flash-read-cache/
http://www.settlersoman.com/what-is-and-how-to-configure-vmware-vsphere-flash-read-cache-vfrc/
http://www.vladan.fr/vmware-vflash-read-cache-vfrc/
