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https://issues.apache.org/jira/browse/HDFS-5442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13923265#comment-13923265
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Colin Patrick McCabe commented on HDFS-5442:
--------------------------------------------
Log-shipping is implemented by many databases, including all the popular
open-source databases such as Postgres and MySQL. However, HDFS is not a
database and doesn't have physio-logical logs in the same sense as those
projects.
What we do have is blocks, which have to be replicated in both places, and of
course the edits. Check out the part of the design doc that deals with
MIRROR_DATANODE_AVAILABLE, etc. stuff to see how the DataNode side of things is
handled.
This design also includes the concept of synchronous replication, something I
haven't seen used with MySQL or postgres.
> Zero loss HDFS data replication for multiple datacenters
> --------------------------------------------------------
>
> Key: HDFS-5442
> URL: https://issues.apache.org/jira/browse/HDFS-5442
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Avik Dey
> Attachments: Disaster Recovery Solution for Hadoop.pdf, Disaster
> Recovery Solution for Hadoop.pdf
>
>
> Hadoop is architected to operate efficiently at scale for normal hardware
> failures within a datacenter. Hadoop is not designed today to handle
> datacenter failures. Although HDFS is not designed for nor deployed in
> configurations spanning multiple datacenters, replicating data from one
> location to another is common practice for disaster recovery and global
> service availability. There are current solutions available for batch
> replication using data copy/export tools. However, while providing some
> backup capability for HDFS data, they do not provide the capability to
> recover all your HDFS data from a datacenter failure and be up and running
> again with a fully operational Hadoop cluster in another datacenter in a
> matter of minutes. For disaster recovery from a datacenter failure, we should
> provide a fully distributed, zero data loss, low latency, high throughput and
> secure HDFS data replication solution for multiple datacenter setup.
> Design and code for Phase-1 to follow soon.
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