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https://issues.apache.org/jira/browse/HBASE-11860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14115420#comment-14115420
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Esteban Gutierrez commented on HBASE-11860:
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[~busbey]:
{quote}
Is your proposal that we adopt a position of always being able to upgrade to a
released version from any supported version at the time of release?
{quote}
Not across all versions but at least the set of versions actively in use. I've
seen that HBase production clusters life is around 2 years with the same
version and sometimes do major upgrades skipping a couple of intermediate
versions, e.g 0.20 -> 0.94, 0.90 -> 0.94, 0.94 -> 0.98. At least we should
support upgrades from previous releases to HBase 1.x.
{quote}
Since our upgrade docs expressly call out not supporting this kind of
upgrades....
{quote}
I think if we have the functionality to migrate a cluster from 0.90 to 0.98
then we should carry that functionality at least to HBase 1.x. Since 0.96 has
been EOL'd I think it should be fine to keep that functionality a little
longer.
[~stack]
{quote}
First off, what Sean says "...our upgrade docs expressly call out not
supporting this kind of upgrades...." That said, it seems going 0.94 to 1.0
wouldn't take much work. If it is just a case of leaving around some deprecated
APIs and restoring old scripts removed in zeal, I'd be game for testing and
making sure it basically works.
{quote}
Thats right, basically the old UpgradeTo96 "works" and it could be required
that the upgrade should be done first to use the old ZK based assignment so
existing znodes could be migrated, then users can opt to use the zk-less
assignment. If using the zk-less assignment we only need to migrate the HBase
filesystem to the new layout.
P.S. +1 I think we can bring this discussion into the dev@ mailing list.
> Restore UpgradeTo in order to upgrade a HBase cluster to the latest release
> ---------------------------------------------------------------------------
>
> Key: HBASE-11860
> URL: https://issues.apache.org/jira/browse/HBASE-11860
> Project: HBase
> Issue Type: Improvement
> Components: HFile, master
> Reporter: Esteban Gutierrez
> Assignee: Esteban Gutierrez
> Fix For: 0.99.0, 2.0.0
>
>
> Users should have the option to upgrade to a newer release of HBase without
> performing a transitive upgrade to HBase 0.96 (EOL'd) or HBase 0.98 and then
> HBase 1.x or 2.x
> In HBASE-11611 UpgradeTo96 was removed and it won't be possible to migrate a
> HBase 0.94 cluster to HBase 1.x or 2.x without the extra step.
> Initially we can restore part of the functionality of the tool supporting
> migration to namespaces and report for the existence of any HFileV1 file and
> ZKDataMigrator could be safely removed.
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