You are viewing a plain text version of this content. The canonical link for it is here.
Posted to mapreduce-issues@hadoop.apache.org by "Ramkumar Vadali (Commented) (JIRA)" <ji...@apache.org> on 2011/12/01 17:30:40 UTC
[jira] [Commented] (MAPREDUCE-3361) Ability to use
SimpleRegeratingCode to fix missing blocks
[ 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