On March 17, I'll be leaving Red Hat. On April 3, I'll be starting at Facebook. I will not be leaving the Gluster project.
I've drafted two much longer posts explaining the reasons for this change, but I'll try to keep this one short. It's not a reflection on Red …
read moreRandy Bias has taken it upon himself to explain that vendor lockin is unavoidable. How surprising that someone who works for one of the most aggressively proprietary vendors in the storage space would say such a thing, with a healthy dose of sneering about unicorns and Santa Claus thrown in …
read more"POSIX is obsolete." If you're a filesystem developer, you've probably heard that many times. I certainly have. It doesn't tell me anything I didn't already know about POSIX, but it does tell me two things about whoever says it.
They don't know what POSIX is.
They're lazy.
To the first …
read moreAs a systems programmer, I get to work with a lot of old-fashioned code and tools. The code base I work on every day is in C, complete with manual memory management and constant checking of return values instead of exceptions. Heck, the Gluster coding style even involves using "goto …
read moreToday I ran for the 200th time this year, fulfilling a promise I'd made to myself ten months ago. That makes me very happy. To make it extra special, I deliberately (since a couple of weeks ago) scheduled my runs so that #200 would be during the Genesis Battlegreen 5K …
read moreThere's a theme I keep coming back to lately, of the relationship between hardware and software and how that relates to recent industry developments such as the acquisition of EMC by Dell. It has shown up for me on The Register, on StorageMojo, and last night on Twitter, so it …
read moreI still consider myself a bit of a running n00b. Several months ago, I was even more of one - so much so that I kept running through one of the worst winters anyone here seems able to remember. Paradoxically, that n00b decision seems to have left me in the position …
read moreAbout a year ago, I started running. I say "about" a year because I don't know the exact date. I know it was early July, so it's not quite a year, but I feel like writing about it now so here goes.
A year ago, I knew nothing. I didn't …
read moreSeveral years ago, Amazon created something called S3 - Simple Storage Service. The "simple" part was based on the premise that distributed file systems are too complex, inhibiting scalability while providing too little marginal value to users. According to that theory, a system with a simpler API and semantics (e.g …
read moreI really don't want to get in the middle of the "HTTPS Everywhere" debate, but a recent message on the topic by Roy Fielding (of REST fame) really bothered me, so I'll add my voice to the chorus anyway. Let's start with the non-technical problem with that email, just to …
read moreThere's a lot of hype around distributed file systems and their relatives, such as object stores. Every week, it seems, there's a new project claiming to be the the fastest, most scalable, most robust, most space-efficient distributed file system ever, sweeping all precursors before it. Nine times out of ten …
read moreUsually, when anyone in government tries to do anything about issues of equality or fairness, the techie-libertarian reaction is to complain about "legislating equal outcomes" and invoke the spectre of Harrison Bergeron as proof. (Hint: it's fiction!) For some reason, "neutrality" doesn't get the same reaction even though it's a …
read moreOf all the projects I've proposed or worked on for GlusterFS, New Style Replication (NSR) is one of the most ambitious. It has two major goals:
Improved handling of network partitions
Improved performance, both normally and during repair
Personally, I consider the improved partition handling to be the more important …
read moreMany people think of erasure coding as equivalent to replication, but with better storage utilization. Want to store 100TB of data with two-failure survivability? With replication you'll need 300TB of physical storage; with 8+2 erasure coding you'll need only 125TB. Yeah, sure, there's a performance downside, but from a …
read moreJust some random thoughts from an email I sent recently, plus a bonus SCSI war story.
read moreAs the PVFS folks said long before I came along, some POSIX requirements are inappropriate for a distributed file system. I agree with that, but not with the object-store folks who claim that the …
One of the most useful metaphors in software engineering is Ward Cunningham's technical debt. Definitions and interpretations vary, but technical debt is basically all the stuff you're going to fix later because you were in too much of a hurry to do it right the first time. We all know …
read moreA recent discussion on the GlusterFS development mailing list got a bit hung up on the issue of what is or is not a "DSO" (Dynamically Shared Object). This is one of a many issues with dynamic linking and dynamic loading that I've seen cause problems before, in large part …
read moreBecause of what I do for $dayjob, I hear a lot about "scale out" vs. "scale up" in various contexts. Also because of what I do for $dayjob, I get to read a lot of code. Some of it's new and clean. Some of it's . . . not. That's only partly a …
read more(...and now for something completely different.)
Back in July, I started running. That would not be a particularly notable statement for many people, but most people haven't detested running all their lives and avoided it for thirty years. Instead, I've used stairclimbers and ellipticals for many years, but I've grown …
read moreForgive me, Lord, for I have sinned.
I have written distributed systems in languages prone to race conditions and memory leaks.
I have failed to use model checking when I should have.
I have failed to use static analysis when I should have.
I have failed to write tests that …
Without further ado...
Never heard of it.
Yeah, I hear all the hipsters yammering about it.
I checked out the docs and examples once.
I used it for a side project.
We're using it for some new projects at work.
We're using it in production.
We're using it in production …
I've written and talked many times about storage benchmarking. Mostly, I've focused on how to run tests and analyze results. This time, I'd like to focus on the parts that come before that - how you set up the system so that you have at least some chance of getting a …
read moreEvery month or two, someone comes along and claims to be the new Best Thing Ever in distributed file storage. More often than not, it's just another programmer who recently discovered things like consistent hashing and replication, then slapped together another HTTP object store because that's what people nowadays do …
read moreI know a lot of people are going to be asking me about Red Hat's acquisition of Inktank, so I've decided to collect some thoughts on the subject. The very very simple version is that I'm delighted. Occasional sniping back and forth notwithstanding, I've always been a huge fan of …
read moreThis afternoon, I'll be giving a talk about (among other things) my current project at work - New Style Replication. For those who don't happen to be at Red Hat Summit, here's some information about why, what, how, and so on.
First, why. I'm all out of tact and diplomacy right …
read moreThe other day, I was talking to a colleague about the debate within OpenStack about whether to chase Amazon's AWS (what another colleague called the "failed Eucalyptus strategy") or forge its own path. It reminded me of an idea that was given to me years ago. I can't take credit …
read moreIn the last few days, I had an interesting exchange on Twitter about the concept of data gravity. For convenience, I'll include the relevant parts here.
Mat Ellis: Interesting piece by @mjasay link … @randybias is right on the money, data gravity is already a big deal on the cloud
A lot of people have asked when GlusterFS is going to have support for tiering or Hierarchical Storage Management, particularly to stage data between SSDs and spinning disks. This is a pretty hot topic for these kinds of systems, and many - e.g. Ceph, HDFS, Swift - have announced upcoming support …
read moreWay back when I was a young pup, either in college or after that but before I started my career, I got to use an operating system called MTS. That stands for Michigan Terminal System. It was created to run on IBM (and later Amdahl) mainframes, when U of M …
read moreThis is a story about the dark side of moving your stuff into the cloud. It does have a (reasonably) happy ending, but along the way there are some important lessons to be learned about the relationship between cloud users and cloud providers, and how it's possible for people on …
read moreFor a while now, Kyle Kingsbury has been doing some excellent work evaluating the consistency and other properties of various distributed databases. His latest target is Redis. Mostly I agree with the points he makes, and that Redis Cluster is subject to inexcusable data loss, but there is one point …
read moreThis was inspired both by a blog post elsewhere and by a nice email I got this morning thanking me for this blog (thanks Tristan). It seems like we all fail to give thanks, and nowhere more so than in the "gift economy" of open source. I'll start with all …
read moreI was around when shared libraries were still a new thing in the UNIX world. At the time, they seemed like a great idea. On multi-user systems like those I worked on at Encore, static linking meant not only having a separate copy of the same code in every program …
read moreWhen I wrote about how local filesystems suck a while ago, it sparked a bit of debate. Mostly it was just local-filesystem developers being defensive, but Dave Chinner did make the quite reasonable suggestion that I could help by proposing a better alternative to the fsync problem. I've owed him …
read moreIt's nice to see more people becoming aware that IOPS are not the be-all and end-all of storage performance. Unfortunately, as with all consciousness raising, the newest converts are often the ones that take things too far. Thus, we get extreme claims like IOPS Are A Scam or Storage Myths …
read moreEver since one of the talks at LISA, I've been thinking about secure email. My thoughts are nowhere near complete, but I need to get them out of my head and I do that by writing about them. Apologies in advance.
I've actually been thinking for many years about how …
read moreI've written before about some people's mania for object storage as an alternative to blocks and files. It's a valid model, but I do think its benefits are being pretty drastically oversold. Often there's a lot of FUD about distributed filesystems in particular, from people who clearly don't know the …
read more(This started as a Hacker News discussion about an article on Advogato. The articles title/premise is "Why You Need STONITH" where "STONITH" means "Shoot The Other Node In The Head" and is an important concept in old-school HA. I might even have been present when the acronym was coined …
read moreIn April of '89 I left my family and friends to move from Michigan to Massachusetts for a programming job. The new job paid twice as much as my first programming job had, which means three times as much as I was making since that company laid me off, so …
read moreModel checking is one of the most effective tools available for reducing the prevalence of bugs in highly concurrent code. Nonetheless, a surprising number of even very smart and very senior software developers and architects seem to know about it. Of the many such people I've worked with over the …
read moreI've often said that open-source distributed storage solutions such as GlusterFS and Ceph are on the same side in a war against more centralized proprietary solutions, and that we have to finish that war before we start fighting over the spoils. Most recently I said that on Hacker News, in …
read moreA while ago, I got an Ergotron WorkFit-S sit/stand monitor mount. I love it, and have talked about it to plenty of people. Yesterday I joined a Hacker News discussion about standing desks, and it left me with some thoughts that I'd rather share here than there, so here …
read moreDistributed filesystems represent an important use case for local filesystems. Local-filesystem developers can't seem to deal with that. That, in a nutshell, is one of the most annoying things about working on distributed filesystems. Sure, there are lots of fundamental algorithmic problems. Sure, networking stuff can be difficult too. However …
read moreTo a first approximation, "software engineering" refers to all of the things you need to know when you take "programming" and try to scale it up - more code, more people, more time. You don't need an a civil engineer to dig a latrine, but you'd better have one to design …
read moreIt's time to let some cats out of some bags. As my loyal readers (yeah right) have surely noticed, things have been quiet around here. Part of that has been the result of vacations and such, but also there's a lot of stuff I just haven't felt ready to write …
read moreAnd now for something completely different...
As part of my job - educating and evangelizing and whatever else you call it - I travel a fair amount. I know there are other people who travel ten times as much as I do, but then there are many more who travel less than …
read moreThis should be a pretty familiar story to anyone in high tech by now. Startup makes something cool, becomes a target for patent litigation from what we used to call an NPE (Non Practicing Entity). Apparently the new term is PAE (Patent Assertion Entity) but I prefer an even more …
read moreSometimes people ask me why I always use small synchronous writes for my performance comparisons. Surely (they say), there are other kinds of operations that are more common or more important. Yes there are (I say), and don't call me Shirley. But seriously, folks, there are definitely other kinds of …
read moreOne of the problems with measuring and comparing performance of scalable systems is that any workload capable of producing meaningful results is going to be highly multi-threaded, and most developers don't know much about how to collect or interpret the results. After all, they hardly ever get any training in …
read moreWe're moving to an "agile" development process at work. Yes, we're becoming scrumbags. ;) One of the terms that really bothers me is "sprint" because I think of a sprint as a flat-out effort. That means minimal eating, sleeping, or time with family. Even hard-core hackers rarely do that for two …
read moreThere are many things that differentiate a true software engineer from a mere programmer. Most of them are unpleasant - planning releases, reviewing designs or code, testing, release engineering, and so on. One of the most odious tasks is packaging software. I'll admit that it's an area where my self-discipline sometimes …
read moreI was sad that I had to miss RICON East, because I knew they had a lot of great speakers lined up. I really liked James Hughes's presentation, but must take issue with slide 15.
read moreMetadata Servers
Required by traditional filesystems (POSIX) to translate names to sectors
Hard to scale …
You might have noticed that things look a bit different around here. OK, if you're reading this in an RSS reader then maybe not, but otherwise it's kind of obvious. I've switched platforms yet again, because I was feeling a bit blocked. Publishing new stuff using my static-wordpress technique was …
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