Randy 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"POSIX is obsolete."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.
To the first …read more
Several 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 more
There'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 more
Of 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 more
Many 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 more
Just some random thoughts from an email I sent recently, plus a bonus SCSI war story.
As 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 …
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 more
Every 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 more
I 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 more
This 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 more
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 more
Way 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 more
When 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 more
It'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 more
I'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
I'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 more
Distributed 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 more
It'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 more
Sometimes 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 more
One 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 more