Bug #40847 Sparse initialization of fragment-log-files can cause future problems

Submitted:	19 Nov 2008 10:06	Modified:	19 Nov 2008 16:40
Reporter:	Jonas Oreland	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Cluster: Cluster (NDB) storage engine	Severity:	S3 (Non-critical)
Version:		OS:	Any
Assigned to:	Jonas Oreland	CPU Architecture:	Any

Description:
Whdn ndb starts intial, it will initialize the fragment logfiles (redo log)
Currently they are initialized sparsely (i.e not all bytes are written)

This *might* cause a problem, wrt to disk-usage and 
customers has seen spurious io-errors on later writes to redo-log
on some linux-kernel versions, that we suspect might be related to sparse-files

How to repeat:
.

Suggested fix:
This patch introduces a new config variable
InitFragmentLogFiles=full

which will cause the files to be fully initialized during initial (node) start.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/59178

2753 Jonas Oreland	2008-11-19
      ndb - bug#40847 - Add config for full initialization of fragment logfiles

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/59180

2754 Jonas Oreland	2008-11-19
      ndb - bug#40847 - Add config for full initialization of fragment logfiles

Pushed into 5.1.29-ndb-6.3.19  (revid:jonas@mysql.com-20081119101301-5grwuquno50iyiao) (version source revid:jonas@mysql.com-20081119101301-5grwuquno50iyiao) (pib:5)

Pushed into 5.1.29-ndb-6.4.0  (revid:jonas@mysql.com-20081119101301-5grwuquno50iyiao) (version source revid:jonas@mysql.com-20081119110117-7stnh2ae76323lw6) (pib:5)

Documented bugfix in the NDB-6.3.19 changelog as follows:

        When performing an initial start of a data node, fragment
        log files were always created sparsely -- that is, not all bytes were
        written. Now it is possible to override this behavior using the new
        InitFragmentLogFiles configuration parameter.

Documented InitFragmentLogFiles parameter in http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-ndbd-definition.html and related places in Cluster chapter - see http://lists.mysql.com/commits/59250

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