Knot DNS server installation problem configure: error: liburcu not found

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I wanted to test out high-performance Knot DNS server and had problem while installing it on Centos 6.2 64-bit platform. The installation died with the error:

configure: error: liburcu not found

After some minutes of research, I found userspace urcu packages available for downloads at:

Debian and Ubuntu Linux distributions does have these packages in their repositories.… Read the rest of this entry »

Time is running out for IPv4 addresses – get PI space while you still can

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Ripe will soon stop assigning PI IPv4 address blocks so you should act fast. You can get an IPv4 /24 PI space for multihoming purpose from Ripe and comply with their allocation policies if you need this space for multihoming.

Ps. This is my first blog post from Android phone!… Read the rest of this entry »

set_real_ip_from and real_ip_header settings for Nginx

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A few weeks ago we got a customer with multiple remote proxy servers accelerating customer’s web site for caching and performance issues. As always, I use Nginx as a front end and forwarding all dynamic queries (PHP) to back-end Apache/PHP for processing. And we hit the wall with getting the real client IP and pass it to the back-end Apache so that all posts and comments do show real client IP address. Hey, site admin requires blocking spamming IP blocks as well as flooders!

Front end proxy servers were already set-up to send X-Forwarded-For header with real client IP address.… Read the rest of this entry »

Memcached replication for data redundancy

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A lot of high performance web sites use memcached to speed up caching and serve content much faster to the web visitors. By default memcached doesn’t offer any data redundancy and no replication feature – memcached uses server RAM to store all data and if the server hardware fails or it is rebooted all data that’s stored in the memcached daemon will be lost. In order to increase memcached data redundancy and offer high availability you should check out RepCached (Web site: ) – it offers multi-master and asynchronous replication for 1.2.x memcached versions.

You can use Layer-4 load … Read the rest of this entry »

Vmware Vsphere error – A specified parameter was not correct spec.sharesinfo.shares

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I tried to edit resource allocation settings and got the following error using Vmware Infrastructure client:

A specified parameter was not correct spec.sharesinfo.shares

To fix the problem and edit resource allocation you should edit values directly from the virtual machine

Login in as Administrator into Vmware Virtual Center using Vmware Infrastructure client. Select the virtual machine you want to modify. Edit Settings. Click Resources tab. Modify the required resource values as required.… Read the rest of this entry »

G-WAN super performance web server daemon


At LKJ.NET blog we usually cover new technologies that allow to scale your web site to new heights. A few weeks ago I spot a new and promising star in the universe – G-WAN web server daemon/software. From the benchmarks it claims to be the fastest web server daemon available on the planet easily beating Nginx and Lighhtpd with a large margin (3-4 times usually). It can easily saturate 10G network up link by serving static content and is ideal for Web 2.0 noSQL stores and similar technologies where phenomenal high speed and low latency is a must.

G-WAN is … Read the rest of this entry »

curl-loader installation from source on Centos 5.6

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For those who are having problems installing curl-loader under Centos platforms please read this guide.

This guide applies to Centos 5.5 and 5.6 versions, 64-bit platforms.

Install the following packages:

yum install libevent libevent-devel

Download curl-loader from:

replace in Makefile

Run with root user:

make install

If you are getting the following error:

curl-loader: error while loading shared libraries: cannot open shared object file: No such file or directory

you are missing c-ares can try to install from Centos yum repository:

yum install c-ares

or download source from:

and curl-loader … Read the rest of this entry »

Been a bit busy, sorry

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Sorry guys, I’ve been a bit busy lately working on Vmware migrations and doing a horizontally scalable web platform. I will have new technical posts published shortly that will include Linux Virtual Server (LVS) configs and UCARP fail-over as well as load balancing and SSL acceleration using Nginx.… Read the rest of this entry »

Increasing httperf maximum number of open descriptors from 1024 to 65535

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By default httperf on Linux compiles with 1024 open descriptors and that can be a problem when you plan to test high bandwidth and many concurrent connection web servers.

For safety you can edit /etc/security/limits.conf however you will also need to change the following file before you compile httperf software:


and find the following line:

/* Number of descriptors that can fit in an `fd_set’. */
#define __FD_SETSIZE 1024

and replace it to

#define __FD_SETSIZE 65535

Now you can compile httperf.
The original string that’s displayed when you run httperf without editing typesizes.h definition file:

httperf: maximum number of

Read the rest of this entry »

Playing around with Linux Virtual Server (LVS)

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I haven’t disappeared folks – I’ve been playing around with Linux Virtual Server (LVS) in the last days and it’s been actually a great experience. Please expect LVS Layer 4 load balancing posts very shortly.

I am currently using Centos 5.6 version with built in IPVS module, but will be compiling custom kernel for best performance. Please hold on – I will have new posts shortly.… Read the rest of this entry »