What are the advantages and disadvantages of OpenSource Tech solutions (Network Monitoring,Backup etc)?

Open Source tools are most custamizable, and if your know the technology you can really make it do wonders.

Most of the current date popular solutions have started as open source projects and now they are running under some vendor or support group as commercial products.

Only challenge is that it takes time and effort to configure it properly and use it properly, nothing comes as out-of-box.