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