Aggregated news from external sources
In a Ceph cluster with low bandwidth, the root disk of an OpenStack instance became extremely slow during days. When an OSD is scrubbing a placement group, it has a significant impact on performances and this is expected, for a … Continue reading →
For more than a year, Ceph has become increasingly popular and saw several deployments inside and outside OpenStack. For those of you who do not know Ceph is unified, distributed and massively scalable open source storage technology that provides several ways to access and consume your data such as object, block and filesystem. The community and Ceph itself has greatly… Read more →
A datacenter containing three hosts of a non profit Ceph and OpenStack cluster suddenly lost connectivity and it could not be restored within 24h. The corresponding OSDs were marked out manually. The Ceph pool dedicated to this datacenter became unavailable … Continue reading →
End of last year, a new puppet-ceph module was bootstrapped with the ambitious goal to re-unite the dozens of individual efforts. I’m very happy with what we’ve accomplished. We are making progress although our community is mixed, but more importantly, … Continue reading →
The benchmark described for Intel Xeon is run with a Highbank ARMv7 Processor rev 0 (v7l) processor (the maker of the processor was Calxeda ), using the same codebase: The encoding speed is ~450MB/s for K=2,M=1 (i.e. a RAID5 equivalent) … Continue reading →
Today is the second day of the Ceph Developer Summit (CDS) for the Giant and Hammer release. We had already several interesting topics and discussions yesterday on the first day.It’s 01:00 in CEST, so now is the time for you to join if you are interest…
Note: this is only useful for people with access to the Ceph lab. When running a Ceph integration tests using teuthology, it may fail because of a DNS resolution problem with: $ ./virtualenv/bin/teuthology-suite –base ~/software/ceph/ceph-qa-suite \ –suite upgrade/firefly-x \ –ceph … Continue reading →
I experimented with Taobao’s fork of nginx, Tengine, in front of an object storage cluster. I was surprised by the results.
I’ve always been a fan of nginx, it was love at first sight.
I tend to use nginx first and foremost as a reverse proxy server for web
content and applications. This means that nginx sends your request to
backend servers and forwards you their response.
Some examples of backend servers I use:
Now, the cool thing is that these backend servers are good at what they
do: serve code and applications written in specific languages.
Mix an awesome, lightweight, proxy and an awesome backend server, you’re
in for some serious performance.
This is in contrast to Apache that has an approach with modules: it
tries to do everything itself – jack of all trades, master of none.
Enough of nginx, let’s talk about Tengine.
Ever heard of Taobao ? I’ll be honest, I hadn’t until fairly
It turns out they are number 8 on Alexa’s top websites, right in
front of Twitter.
When China makes up almost 20% of the World’s population, even a
small penetration on the market is in fact huge by all means.
Tengine is a fork of nginx created by the team over at Taobao. There’s a
lot of features in Tengine that do not (yet) exist in nginx and some
features that upstream maintainers said they would not implement.
Some highlights include:
Long story short, Object storage is a mean of storing data online
and make it easily accessible with the help of APIs.
Example of products using this technology include Dropbox, Google Drive,
Microsoft OneDrive or Amazon S3.
Owncloud is also a good open source and self-hosted alternative front
end to Object Storage.
They’re both similar in that you upload files to a proxy server – a
Swift proxy server or a Ceph RADOS Gateway server. These proxy servers
take care of sending the files back to storage servers that ensure data
is distributed and replicated to ensure the high availability and
redundancy of your data.
It looks a bit like this:
+-----------+ +--> | Storage | | +-----------+ | +-----+ File +-------+ | +-----------+ | You | +----> | Proxy | +-----> | Storage | +-----+ +-------+ | +-----------+ | | +-----------+ +--> | Storage | +-----------+
Now, in a highly available and distributed environment, you might have
dozens or hundreds of storage and proxy servers. There are a lot of
options out there, you might have something like haproxy, pound
or nginx for load balancing.
With a load balancer in front of your proxy servers, your setup now
looks like this:
+-------+ +-----------+ +--> | Proxy | +--+--> | Storage | | +-------+ | +-----------+ | | +-----+ File +---------------+ | +-------+ | +-----------+ | You | +----> | Load Balancer | +-----> | Proxy | +-----> | Storage | +-----+ +---------------+ | +-------+ | +-----------+ | | | +-------+ | +-----------+ +--> | Proxy | +--+--> | Storage | +-------+ +-----------+
I noticed a problem when using nginx as a load balancer in front of
servers that are the target of large and numerous uploads. nginx buffers
the request of the body and this is something that drives a lot of
discussion in the nginx mailing lists.
This effectively means that the file is uploaded twice. You upload a
file to nginx that acts as a reverse proxy/load balancer and nginx waits
until the file is finished uploading before sending the file to one of
the available backends. The buffer will happen either in memory or to an
actual file, depending on configuration.
Tengine was recently brought up in the Ceph mailing lists as part of
the solution to tackling the problem so I decided to give it a try and
see what kind of impact it’s unbuffered requests had on performance.
I uploaded a 1GB file to an Object storage cluster with nginx 1.6.0 in
front. I then swapped it out for Tengine 1.5.2 and tried again. Swapping
webservers was as simple as uninstalling Nginx and installing Tengine
from a package I built. The configuration I had was 100% compatible,
I only had to add configuration to disable request buffering.
The layout looked like this:
+----+ 1GB File +---------------+ +-------+ +-----------+ | Me | +---------> | Load Balancer | +---> | Proxy | +---> | Storage | +----+ +---------------+ +-------+ +-----------+ 1Gbps 1Gbps
With nginx, the upload took 1 minute 13 seconds.
With Tengine, the upload took 41 seconds.
That’s a difference of more than 30 seconds !
I was blown away by the difference disabling the buffering made.
Tengine really was a drop-in replacement to Nginx, much like
MariaDB 5.5 is for MySQL.
This blog now runs Tengine, perhaps there is also a
bright future ahead of Taobao’s team ?
It might just start making waves outside of China.
Let’s wait and see.
Six months have passed since Hong Kong and it is always really exciting to see all the folks from the community gathered all-together in a (bit chilly) convention center. As far I saw from the submitted and accepted talks, Ceph continues its road to the top. There is still a huge growing interest about Ceph. On tuesday May 13th, Josh… Read more →
On a Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz processor (and all SIMD capable Intel processors) the Reed Solomon Vandermonde technique of the jerasure plugin, which is the default in Ceph Firefly, performs better. The chart is for decoding erasure … Continue reading →