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https://issues.apache.org/jira/browse/HDFS-15477?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz-wo Sze updated HDFS-15477:
------------------------------
Description:
Snapshot deletion has caused a few bugs earlier such as HDFS-13101 and
HDFS-15313. In this JIRA, we propose a configurable feature for enforcing
ordered snapshot deletion -- only the earliest snapshot is actually deleted
from the file system. The other snapshots are only marked as deleted. They
will be actually deleted from the file system until all the earlier snapshots
are deleted.
The reason of enforcing ordered snapshot deletion is based on the observation
that the logic of deleting the earliest snapshot is much simpler since the
prior snapshot does not exist. All the previous bugs are caused by removing
inodes from the prior snapshot.
One drawback of ordered snapshot deletion is that the resources are not yet
released for deleting the non-earliest snapshots since they are only marked as
deleted but not actually deleted.
was:
Snapshot deletion has caused a few bugs earlier such as HDFS-13101 and
HDFS-15313. In this JIRA, we propose enforcing ordered snapshot deletion --
only the earliest snapshot is actually deleted from the file system. The other
snapshots are only marked as deleted. They will be actually deleted from the
file system until all the earlier snapshots are deleted.
The reason of enforcing ordered snapshot deletion is based on the observation
that the logic of deleting the earliest snapshot is much simpler since the
prior snapshot does not exist. All the previous bugs are caused by removing
inodes from the prior snapshot.
One drawback of ordered snapshot deletion is that the resources are not yet
released for deleting the non-earliest snapshots since they are only marked as
deleted but not actually deleted.
> Enforce ordered snapshot deletion
> ---------------------------------
>
> Key: HDFS-15477
> URL: https://issues.apache.org/jira/browse/HDFS-15477
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: snapshots
> Reporter: Tsz-wo Sze
> Assignee: Tsz-wo Sze
> Priority: Major
>
> Snapshot deletion has caused a few bugs earlier such as HDFS-13101 and
> HDFS-15313. In this JIRA, we propose a configurable feature for enforcing
> ordered snapshot deletion -- only the earliest snapshot is actually deleted
> from the file system. The other snapshots are only marked as deleted. They
> will be actually deleted from the file system until all the earlier snapshots
> are deleted.
> The reason of enforcing ordered snapshot deletion is based on the observation
> that the logic of deleting the earliest snapshot is much simpler since the
> prior snapshot does not exist. All the previous bugs are caused by removing
> inodes from the prior snapshot.
> One drawback of ordered snapshot deletion is that the resources are not yet
> released for deleting the non-earliest snapshots since they are only marked
> as deleted but not actually deleted.
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