New answers tagged high-availability
To answer your questions: RAID5 is not advisable, period. A single bad read during a rebuild kills your entire array. This is more of an issue with HDDs than SSDs, but it's still a consideration. RAID10 is generally the best option, but RAID6 (dual-parity) can also do quite well. You're comparing Jaguars to Hyundais, there. SSDs have better random access, ...
The easiest way to distribute traffic would be to create two virtual routers. Each physical router is primary for one of the virtual routers and secondary for the other. This will not be completely transparent to the LAN. But by assigning two different IPs to the virtual routers, you will be able to distribute the clients among the two virtual routers. This ...
A more network-centric solution would be use two DNS servers with the same (dedicated) IP and Anycast routing. (I haven't noticed this answer in this thread so far, but that's what is used here.) As long as both are up, the nearest server is used. If one goes down, traffic for that IP will be routed to the other node until it comes up again. This especially ...
For me the error HA is not enabled for this namenode was resolved when I corrected the hdfs-site.xml config file, where I had mistakenly mentioned 3 namenode-id for a single nameservice-id. Ha configuration accepts only 2 namenode-ids.
I would use DFS and setup replication between the servers, you can set it for one way or full mesh replication. DFS Blog from MS.
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