hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Ramkumar Vadali (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-3361) Ability to use SimpleRegeratingCode to fix missing blocks
Date Thu, 01 Dec 2011 16:30:40 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-3361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13160969#comment-13160969
] 

Ramkumar Vadali commented on MAPREDUCE-3361:
--------------------------------------------

It will also be nice to have this code be backwards compatible with existing Reed-Solomon
parity files. If there is an existing Reed-Solomon parity file, the code can identify that
by counting the number of parity blocks with the expected number of Reed-Solomon parity files.
This is doable because the additional XOR parity blocks will increase the total number of
parity blocks by a deterministic number. Thus this code will be able to handle existing Reed-Solomon
parity files and will generate new files with additional XOR blocks.
                
> Ability to use SimpleRegeratingCode to fix missing blocks
> ---------------------------------------------------------
>
>                 Key: MAPREDUCE-3361
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3361
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: contrib/raid
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>
> ReedSolomon encoding (n, k) has n storage nodes and can tolerate n-k failures. Regenerating
a block needs to access k blocks. This is a problem when n and k are large. Instead, we can
use simple regenerating codes (n, k, f) that does first does ReedSolomon (n,k) and then does
XOR with f stripe size. Then, a single disk failure needs to access only f nodes and f can
be very small.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message