Torsten Curdt wrote:
On Jul 30, 2008, at 20:35, Raghu Angadi wrote:
You should always have more than one location (preferably on different
disks) for fsimage and editslog.
On production we do frequent backups. Is there a mechanism from inside
hadoop now to do something like that now? The "more than one location"
bit sounds a little like that.
You can specify multiple directories for "dfs.name.dir", in which case
fsimage and editslog are written to multiple places. If one of these
goes bad, you can use the other one.
See http://wiki.apache.org/hadoop/FAQ#15
Raghu.
A few months back I had a proposal to keep checksums for each record
on fsimage and editslog and NameNode would recover transparently from
such corruptions when there are more than one copies available. It
didn't come up in priority since there were no such failures observed.
You should certainly report these cases and will help the feature gain
more traction.
Will file a bug report tomorrow.
cheers
--
Torsten
