Varnish Cache is a web application accelerator also known as a caching HTTP reverse proxy. You install it in front of any server that speaks HTTP and configure it to cache the contents. Varnish Cache is really, really fast. It typically speeds up delivery with a factor of 300 - 1000x, depending on your architecture. A high level overview of what Varnish does can be seen in the video attached to this web page.
Performance
Varnish performs really, really well. It is usually bound by the speed of the network, effectivly turning performance into a non-issue. We've seen Varnish delivering 20 Gbps on regular off-the-shelf hardware.
Flexibility
One of the key features of Varnish Cache, in addition to it's performance, is the flexibility of it's configuration language, VCL. VCL enables you to write policies on how incoming requests should be handled. In such a policy you can decide what content you want to serve, from where you want to get the content and how the request or response should be altered. You can read more about this in our tutorial.
Further reading
There is a good article describing Varnish Cache on Wikipedia.
Licence and origin
Varnish is free software licensed under a two-clause BSD licence, also known as the FreeBSD licence. The project was initiated in 2005. Varnish Cache 1.0 was released in september 2006.
The name "Varnish"
The name Varnish comes from when the instigator of Varnish spent a long time staring at an art-poster with the word “Vernisage” and ended up checking it in a dictionary, which gives the following three meanings of the word:
r.v. var·nished, var·nish·ing, var·nish·es
- To cover with varnish.
- To give a smooth and glossy finish to.
- To give a deceptively attractive appearance to; gloss over.
T
Squid is free open source application used as a proxy server and web cache daemon originally designed to run on Unix-like systems, it also runs well on Windows-based systems. Squid has a wide variety of uses. Although primarily used for HTTP and FTP, Squid includes limited support for several other protocols including TLS, SSL, Internet Gopher and HTTPS.
To install squid run the command
#yum install squid
After the installation is finish, edit the squid configuration file using a text editor
#vi /etc/squid/squid.conf
Modify or add following squid directives
http_port 3128 transparent
always_direct allow all
Create an ACL (Access Control List) which contains ip address or pool of ip address.
acl lan src 192.168.1.1 192.168.2.0/24
Ip address can be separated by spaces. Squid allow access to LAN and localhost ACL
http_access allow localhost
http_access allow lan
When you are done with your squid, the next step is to configure your Centos as a bridge. Remember that there are number of approach to do your transparent proxy depending on your situation or liking, it is either make your Linux box as a router, do a NAT, re-route traffic coming form port 80 to your proxy server or in
Exactly one year ago two well-known virtualization experts Ruben Spruijt (Solution Architect and CTO at PQR) and Jeroen van de Kamp (Enterprise Architect and CTO at Login Consultants) releasedan independent, non-sponsored performance analysiscomparing ESX 3.5, XenServer 5.0 and Hyper-V 2008. The benchmark, specifically designed to measure desktop virtualization workloads (served by Terminal Services and VDI platforms), was so valid that Citrix decided to embrace the Virtual Reality Check methodology to measure XenDesktop 4 performance. Twelve months later the two are back with a new comparison. This time they put side by side Citrix XenServer 5.5, Microsoft Windows Server 2008 R2 Hyper-V and VMware vSphere 4.0 Update 1, comparing them against their new workload simulator Virtual Session Indexer (VSI) 2.0. The most interesting thing is that all tests were performed on HP hardware equipped with the new Intel Xeon 5500 Series CPUs (codename Nehalem), and compared to Virtual Reality Check 1.0 results obtained on previous generation processors. Once again, if you are involved in a desktop virtualization project this performance analysis is a mandatory reading.Benchmarks: vSphere 4.0 vs XenServer 5.5 vs Hyper-V R2 for Terminal Services and VDI workloads
Performance are almost doubled with both XenServer and vSphere, and with Hyper-V R2, performance are up 154%.
We are looking for 3 PH-LWUG CORE member to help us continue our Mission and Vision for our Community.
Qualifications:
- Your time when we have a meeting and events: Seminar/Trainings
- Willing to share your knowledge
Just PM us if you're interested. Thanks!
More Articles...
Page 1 of 7
