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+date: 2013-02-21
+title: Something from the shadows
+category: Opinions
+---
+
+An intriguing startup came out of stealth mode a few days ago. [Pernix
+Data](https://pernixdata.com/) was founded by Pookan Kumar and Satyam
+Vaghani, both of who were pretty near top of the pile in VMware\'s
+storage team.
+
+What they are offering is, to me at least, a blinding flash of the
+obvious. It is a softweare layer that runs on a VMware hypervisor that
+uses local flash as a cache for whatevery is coming off your main
+storage array. {% img right
+[https://pernixdata.com/images/home\\\_graphic3.png](https://pernixdata.com/images/home\_graphic3.png)
+300 217 %}. That could be an SSD (or multiple) or a PCI-e card.
+
+Reading what they have to say, it is completely transparent to the
+hypervisor, so everything just works. Obviously me being an Open Source
+fanatic I imediately started thinking how I could do this with Linux; it
+took me about 5 minutes.
+
+You take your SAN array and give your LUN to your Hypervisors (running
+KVM obviously, and with a local SSD). Normally you would stick a
+clustered file system (such as GFS2) on that shared LUN. Instead you use
+a tiered block device on top of that LUN. There are two that come
+immediately to mind:
+[Flashcache](https://github.com/facebook/flashcache/) and
+[Btier](https://sourceforge.net/projects/tier/files/).
+
+Finally, you can put your clustered file system on that tiered device. I
+do not have the time or facilities to test this, but I cannot see why it
+would not work. Maybe someone at Red Hat (seeing as they do the bulk of
+KVM and GFS2 development) can run with this and see what happens. What
+their plans are I do not know. It is very early days, maybe they will be
+a success maybe not. As they are both ex-VMware, I would not be at all
+surprised if they get bought back into the VMware fold. Certainly this
+is a functionality that I would have like to have seen in the past.