Hi. By default SecondaryNameNode compacts the meta-data every 60 minutes, correct?
So in your setup, SNN does it every 5 minutes? How reliable is this? Regards. 2009/10/1 Jason Venner <jason.had...@gmail.com> > If you are looking for moment by moment recovery, you need to have multiple > directories, preferably on several devices, for your Namenode edit log > (which is modified for each meta data change) > and also multiple directories for the FS image, which is updated every few > minutes by the secondary Namenode. > > Having one of your directories on NFS will slow your Namenode down some, as > all writes to all devices have to complete before a meta data operation is > finished. I seem to recall that the writes are done in parallel. This does > however give you fast failover. > > The secondary Namenode is a nice repository of 5 + minute old data in the > event of a catastrophic failure or catastrophic user error such as a mass > file removal. > > > On Thu, Oct 1, 2009 at 6:15 AM, Stas Oskin <stas.os...@gmail.com> wrote: > > > Hi. > > > > I'm looking to spread the meta-data writing across several disks, > including > > NFS, to provide greater survivability. > > > > What make sense more - to write NameNode meta-data to NFS, or to write > the > > SecondaryNameNode meta-data to NFS, or a combination of them? > > > > Thanks. > > > > > > -- > Pro Hadoop, a book to guide you from beginner to hadoop mastery, > http://www.amazon.com/dp/1430219424?tag=jewlerymall > www.prohadoopbook.com a community for Hadoop Professionals >
