works for me over many clusters. I haven't tried the 0.20 version though. On Thu, Oct 1, 2009 at 10:48 AM, Stas Oskin <stas.os...@gmail.com> wrote:
> 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 > > > -- 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
