Perlbal can process hundreds of millions of hits daily on a medium hardware server. No wonder it’s used on high load sites like Vox and LiveJournal.

It offers load distribution to multiple back-end servers and different load balancing algorithms that will mostly suit all web site needs. We will be testing this proxy software and compare how does it perform comparing to nginx.

Perlbal web site URL: http://www.danga.com/perlbal/… Read the rest of this entry »

A general system error occurred: The system returned an error. Communication with the virtual machine may have been interrupted.

The above error was displayed in Vsphere Virtual Center client when I tried powering on ta virtual machine that was stopped for RAM changes. This virtual server was running for over a year without any problems. I was scared a bit at the beginning since it was a production server, but after restarting management agents on the Vsphere ESXi server (via console), I was able to power-on this problematic virtual machine.… Read the rest of this entry »

If you are running Novell SLES 11 (32 or 64 bit) OS on Vmware Vsphere platform I have some good news for you. Keeping system time on this platform is very easy as long as you have an external NTP server. Below I have listed necessary configuration steps to perform on SLES 11 for best system time keeping.

Please note that this guide will also apply for SLES 11 installed on a dedicated hardware just skip the Vmware specific configuration.

Disable Vmware Tools time synchronization with the Host under “Edit settings” for the specific virtual machine. This requires virtual machine … Read the rest of this entry »

It’s been a hot topic how to do a recovery after the failure between two remote data centers using Vmware Vsphere and Virtual Center. What if one of the data centers goes down and you want all your virtual machines to be running in a second data center? In this post I am not evaluating Vmware  Site Recovery Manager software that offers data center recovery – I should probably come up with a more detailed information about this software in the near future.

Remember, there will be downtime even if you intend to use Site Recovery Manager – in order … Read the rest of this entry »

There has been debates for years if one large site is much better than 50 small ones. Some folks say the big site wins, some believe multiple small sites do provide advantage. Let’s not get into debates what is better, but let’s look at multiple domain name hosting for SEO.

• Search engines like sites linking to each other on completely different IP subnets. Preferable different data centers and upstream providers – it’s easy for search engine programmers to assume these are two different sites linking each to other.
• Completely different WHOIS records, including owner, address, fax, phones etc. Preferable not

… Read the rest of this entry »

To increase Nginx performance under Solaris OS you should use eventport event model. This will increase your server throughput at least 20%. Give it a try and see what performance it will offer you.

However, don’t forget to install a specific security patch from Sun Microsystems web site.

Example settings for nginx.conf:

events {
    connections   2000; # connection no.
    use eventport;
}

… Read the rest of this entry »

I had a chance to speak with one fellow who asked us to do some in-house testing of using Varnish with WordPress. It might be very interesting because of caching dynamic pages and using ESI properly. I am sure we will do some testing and example set-ups and post about this topic in near future.… Read the rest of this entry »

A few years ago a fully-dedicated 100Mbps up-link for a dedicated server was a dream for many folks. Not anymore! The bandwidth pricing went down drastically, the internet connectivity speed has increased a lot.

Nowadays even a budget dedicated server has 100 Mbps up-link and the question is how much bandwidth you can push?

Let’s look at the typical scenario: a web server hosting a large web site or blog. Since we are interested in maximum bandwidth your server can push using 100Mbps up-link, we will skip the server CPU/RAM/IO load issues that usually is a quite big problem with … Read the rest of this entry »

There are many ways how to upgrade ESXi servers, but below, I will compile a list of update steps I am performing.

We only use ESXi Vsphere 4 version with Standard and Advanced type licenses. All ESXi servers are connection to Virtual Center and managed from there.

1.) Download ESXi installable ISO from Vmware.com web site and burn it in CD
2.) Move all virtual servers to other ESXi hosts using vMotion or shutdown servers and use standard migration
3.) Enter ESXi host in “Maintenance mode”
4.) Disconnect FC storage uplinks
5.) Insert CD in CD tray – boot the … Read the rest of this entry »

In order to correctly use beacon fail-over probing for Vmware vSphere server network connectivity you need:

• 2 physical uplink switches in failover set-up;
• 3 physical uplinks in team per each vSwitch with beacon probing enabled;
• 2 of the uplinks (each going into different uplink switch) must be active and the third physical uplink should be set-up as a Standby adapter.

Beacon probing also works if you are using Vlan trunks. The only difference is that in case of any uplink failure beacon probes will be sent to all vSwitch VLANs increasing traffic a little.

Keep in mind:

You cannot advertise … Read the rest of this entry »