When provisioning, there are two options for namenode device management: use the namenode’s ability to write data to multiple JBOD devices, or write to a RAID device. No matter what, a copy of the data should always be written to an NFS (or similar) mounted volume in addition to whichever local disk configuration is selected. This NFS mount is the final hope for recovery when the local disks catch fire or when some equally unappealing, apocalyptic event occurs.
Namenode data contingency planning.
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