Guys, I am learning that NN doesn't persistently store block locations. Only file names and heir permissions as well as file blocks. It is said that locations come from DataNodes when NN starts.
So, how does it work? Say we only have one file A.txt in our HDFS that is split into 4 blocks 1,2,3,4 (no replication), with block 1-2 residing on DN1 and blocks 3,4 on DN2. When we start NN it reads it metastore and tries to locate and map the locations of 4 blocks of file A.txt?? Andy Kartashov MPAC IT Architecture, Co-op 1340 Pickering Parkway, Pickering, L1V 0C4 * Phone : (905) 837 6269 * Mobile: (416) 722 1787 [email protected]<mailto:[email protected]> NOTICE: This e-mail message and any attachments are confidential, subject to copyright and may be privileged. Any unauthorized use, copying or disclosure is prohibited. If you are not the intended recipient, please delete and contact the sender immediately. Please consider the environment before printing this e-mail. AVIS : le pr?sent courriel et toute pi?ce jointe qui l'accompagne sont confidentiels, prot?g?s par le droit d'auteur et peuvent ?tre couverts par le secret professionnel. Toute utilisation, copie ou divulgation non autoris?e est interdite. Si vous n'?tes pas le destinataire pr?vu de ce courriel, supprimez-le et contactez imm?diatement l'exp?diteur. Veuillez penser ? l'environnement avant d'imprimer le pr?sent courriel
