7 Techniques of Mirroring Website Mirrors:Mirrors simply compare and pull the contentsfrom a single master web site at a regularintervals and make identical contentsavailable on another computer, ideally closerto the users making use of it.
8 Motives for Mirroring Load Balancing - yahoo.co.uk yahoo.co.in High Availability - ADS mirrorsMultilingual replication -Database Sharing –Franchise / Local Versions -quicken.excite.com quicken.comVirtual Hosting - sports.catalogue.com
9 Mirroring IssuesMaintenance of mirror-sites in different geographical locations.Integrity of the mirrored contentsProviding Host-Independent URLS.Initial transfer of dataOptimizationEconomical constraintsProviding Efficient routing
10 Popular Mirroring tools on Unix RSyncWgetMirror
11 Mirroring Experience IUCAA (Inter University Centre For Astronomy and Astrophysics)works closely with ERNET(Educational and ResearchNETwork) to make thisnetwork a content orientednetworkhttp://www.iucaa.ernet.in/
12 ERNET India ? In 1986, then Department of Electronics had initiated a project "ERNET" with thefunding from UNDP. The objective was toestablish and operate a nationwideInternet for the Indian academic andresearch community. Now it has becomea full pledged ISP known as ERNET India.
16 Mirrors available in IUCAA VizieR provides access to the most complete libraryof published astronomical catalogues and data tablesavailable on line, organized in a self-documenteddatabase.
17 Mirrors available in IUCAA The NASA Astrophysics Data System (ADS) maintains four bibliographic databases containing more than 4 million records.
18 VOI Data Archives at IUCAA SDSS Sloan Digital Sky Survey – 1 Tb2MASS 2 Micron All Sky Survey – 194 Gb2dfGRS 2 degree field Galaxy Redshift Survey – 5.5 Gb2QZ 2 Degree field QSO Survey – 630 Mb FIRST Survey Faint Images of Radio Sky at Twenty centimeters – 226 Gb
20 Mirror-site under construction Chandra Data Archive (CDA)424 GB data is available through ftp service. ftp://cdaftp.iucaa.ernet.inIncremental update is being done regularly.Web based CDA service will be provided,once the new release of CXCDS softwareis made available.
21 Acknowledgement Dr. Francois Ochsenbein - VizieR Dr. Guenther Eichhorn and Dr.Alberto Accomazzi - ADSDr. Ramadurai Padmanabhan - CDA