On Thu, Dec 20, 2012 at 12:33 AM, ishan chhabra <ishan.chha...@gmail.com> wrote: > Unfortunately, the checkpoint image that I have has the deletes recorded. I > cannot use it. I do have an image that is 15 days old, which I am currently > running. > > I looked at the my logs and I have the filename, block allocated and > generation stamp. Can you explain to me the importance of the generation > stamp here? Since my hdfs cluster is operational with the old image and I > am writing new data to it, the generation stamp must have been incremented > beyond what it was 15 days ago. If I try to restore a block that we > written, lets say, 13 days ago, there can be generation stamp collision. > So, if I stop my cluster and make the new entries with generation stamp > increments after what is currently in the namenode, will it be ok? Is the > generation stamp stored somewhere in the datanode or the block stored in > the datanode?
The generation stamp is stored by the datanode in the block directory, as part of the .meta filename. For example, if block -8546336708468389550 has genstamp 1002, you would see something like this: cmccabe@keter:/h> ls -l /r/data1/current/BP-380817083-127.0.0.1-1356638793552/current/finalized/*8546336708468389550* total 8 -rw-r--r-- 1 cmccabe users 2025 Dec 27 12:38 blk_-8546336708468389550 -rw-r--r-- 1 cmccabe users 23 Dec 27 12:38 blk_-8546336708468389550_1002.meta cheers, Colin > > Thanks for the clarifications. > > On Wed, Dec 19, 2012 at 10:40 PM, Harsh J <ha...@cloudera.com> wrote: > >> proper INode entries of them to append/recreate your fsimage. They are > > > > > -- > Thanks. > > Regards, > Ishan Chhabra
