We are working on a project for a consulting customer. They’ve hired us to help them figure out where their performance is being “lost”.
Obviously, without naming names or revealing information, I note something interesting about this, that I’ve alluded to many times before.
There is an often profound mismatch between expectations for a system and what it actually achieves.
This is in large part, why we benchmark and test our systems in as real configurations as possible, and report real numbers, while many (most) of our competitors make WAGs at best case/best effort/best condition theoretical numbers.
This said, part of the problem with performance expectations are the assumptions underlying it. One of the things I rail on the current Gluster marketing efforts about, are related to the same assumptions. And these assumptions are used as the basis of statements (and in some cases, marketing materials) that are … wrong … at best.
But its not just Gluster marketing that has this as a problem. These core assumptions are often (completely) wrong for a fairly wide range of things, and yet they are used as the basis for many marketing claims that are, at best, specious. Worse than this, are benchmark tests that are fatally flawed, unrepeatable, or somehow or the other broken, and poorly representative of workloads.
Add it all up and you have no real mechanism to predict performance based upon what is published.
Ok … here’s a simple example. You have a disk. Lets call it a SATA 7.2kRPM drive. You can get 100 MB/s out of it (ok, I know its a little more today, just using easy numbers to make life simpler). If I have 10 of these, I get 1GB/s, right? and 20 will give me 2GB/s. #winning !
Talking about rt. Our support site. Thankfully most of the stuff is in the database with a little customization. Thankfully we want to move from 3.x to 4.x. Annoyingly, this is more work. Thankfully, our web server design is now far more intelligent than in the past. We may simply run it on the web … Read more… and the VM (and its snapshot) managed to get corrupted …