OpenZFS: Reducing ARC Lock Contention

tl;dr; Cached random read performance of 8K blocks was improved by 225% by reducing internal lock contention within the OpenZFS ARC on illumos. Introduction Real World Problems with the ARC Performance: Before Remove the Lists? Solution: Use More Locks! Performance: After Commit Details Appendix 1. Introduction Locks are a pain....
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Open Sourcing of dxData

I’m happy to announce the open sourcing of dxData, available on the Delphix GitHub page. dxData is the JavaScript client library that underlies all client/server communication in our JavaScript-based applications. dxData provides these features: Reactivity: Changes in server data are reflected immediately on the client without an app developer needing to do special work. Unidirectionality:...
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A space map

OpenZFS Code Walk: Metaslabs and Space Maps

I wrote this post about a year ago while to trying to sort out how metaslabs worked with George Wilson. At the time, I found walking through the code with George to be exceptionally helpful, so I’m publishing this in case others find it useful. In OpenZFS, metaslabs are data...
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Device removal

OpenZFS Device Removal

A few of weeks ago, Matt and I integrated OpenZFS device removal into the Delphix downstream repository of Illumos. I first presented this work at the OpenZFS developer summit, but this blog post will provide a high level overview of the feature and some exploration into some of the more...
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OpenZFS Developer Summit 2014: OpenZFS on illumos

The OpenZFS project is growing! The second annual OpenZFS developer summit concluded just under two months ago, and overall I thought it went very well. There was roughly 70 attendees, twice as many as the previous year, and the talks given were very engaging and interesting. I gave a short...
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DTrace OEL Dynamic Language Support

We built DTrace to solve problems; at the start, the problems we understood best were our own. In the Solaris Kernel Group we started by instrumenting the kernel and system calls, the user/kernel boundary. Early use required detailed knowledge of kernel internals. As DTrace use grew—within the team, in Sun...
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Open-source DSP (Delphix Session Protocol)

Delphix is pleased to announce a new addition to its open-source software initiative, Delphix Session Protocol (DSP). DSP is a network framework used by the Delphix Engine. It aims to simplify the development of distributed applications by separating the application “business logic” from underlying “network issues.” In an earlier blog...
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NLM’s Garbage Collection Race

This is the first in (hopefully!) a series of blog posts where I’ll talk about some of the cooler bugs I’ve run into here at Delphix. Let’s start with some background to explain some things that will be handy to know. BACKGROUND Programs occasionally need to synchronize access to files....
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The OpenZFS write throttle

In my last blog post, I wrote about the ZFS write throttle, and how we saw it lead to pathological latency variability on customer systems. Matt Ahrens, the co-founder of ZFS, and I set about to fix it in OpenZFS. While the solution we came to may seem obvious, we...
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ZFS fundamentals: the write throttle

It’s no small feat to build a stable, modern filesystem. The more I work with ZFS, the more impressed I am with how much it got right, and how malleable it’s proved. It has evolved to fix shortcomings and accommodate underlying technological shifts. It’s not surprising though that even while...
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