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https://issues.apache.org/jira/browse/HBASE-8352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13633091#comment-13633091
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Jonathan Hsieh commented on HBASE-8352:
---------------------------------------

I'm suggesting that for future 0.94's (0.94.7 let say) we print a warning if 
the original directory is used.  We decide to warn if hbase detects the 
.snapshot dir is being used to store hbase table snapshot metadata.

bq. See release notes in HDFS-4666 for how ".snapshot" is handled by hdfs with 
snapshot capability.

The release note doesn't say anything that would prevent the ls and potential 
read operations necessary to check and log.

HDFS-4666's release note: "This is an INCOMPATIBLE CHANGE: ".snapshot" becomes 
a reserved inode name so that users cannot create a file/directory with 
".snapshot" as the name. If ".snapshot" is used in a previous version of HDFS, 
it must be renamed before upgrade; otherwise, upgrade will fail." 

HDFS upgrades failing because of existing .snapshot dirs is great.

>From HDFS snapshot design doc / admin usage:  
>https://issues.apache.org/jira/secure/attachment/12551474/Snapshots20121030.pdf
{code}
Deleting a snapshot:
> rm -r <snapshottable_dir_path>/.snapshot/snapname
Listing all the snapshots:
> ls <snapshottable_dir_path>/.snapshot/
{code}

We can ls the .snapshot dir as if it were a normal dir.
                
> Rename '.snapshot' directory
> ----------------------------
>
>                 Key: HBASE-8352
>                 URL: https://issues.apache.org/jira/browse/HBASE-8352
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: Ted Yu
>            Priority: Blocker
>             Fix For: 0.98.0, 0.94.7, 0.95.1
>
>         Attachments: 8352-0.94-v1.txt, 8352-trunk.txt, 8352-trunk-v2.txt
>
>
> Testing HBase Snapshot on top of Hadoop's Snapshot branch 
> (http://svn.apache.org/viewvc/hadoop/common/branches/HDFS-2802/), we found 
> that both features used '.snapshot' directory to store metadata.
> HDFS (built from HDFS-2802 branch) doesn't allow paths with .snapshot as a 
> component
> From discussion on d...@hbase.apache.org, (see 
> http://search-hadoop.com/m/kY6C3cXMs51), consensus was to rename '.snapshot' 
> directory in HBase so that both features can co-exist smoothly.

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