Dear Bryan, Thank you very much for your answers. They are very helpful to me. I will use more nodes (>=5) in future.
From your experience with using Riak, what would your guess be for the time taken to finish all the AAE transfers and be done with the recovery for about 1 TB worth of data (assuming my cluster is otherwise completely idle without any user accessing the cluster during this process and that I am continuously watching the transfers and re-enabling disabled AAE trees gradually )? I am just asking for rough estimate from your past experience ( please quote from your experience with a difference sized cluster / data size too ). My guess is that it will take approx. 2 days or more. Do you concur? Thanks, Leo On Tue, Sep 19, 2017 at 12:41 PM, Bryan Hunt <bryan.h...@erlang-solutions.com> wrote: > (0) Three nodes are insufficient, you should have 5 nodes > (1) You could iterate and read every object in the cluster - this would also > trigger read repair for every object > (2) - copied from Engel Sanchez response to a similar question April 10th > 2014 ) > > * If AAE is disabled, you don't have to stop the node to delete the data in > the anti_entropy directories > * If AAE is enabled, deleting the AAE data in a rolling manner may trigger > an avalanche of read repairs between nodes with the bad trees and nodes > with good trees as the data seems to diverge. > > If your nodes are already up, with AAE enabled and with old incorrect trees > in the mix, there is a better way. You can dynamically disable AAE with > some console commands. At that point, without stopping the nodes, you can > delete all AAE data across the cluster. At a convenient time, re-enable > AAE. I say convenient because all trees will start to rebuild, and that > can be problematic in an overloaded cluster. Doing this over the weekend > might be a good idea unless your cluster can take the extra load. > > To dynamically disable AAE from the Riak console, you can run this command: > >> riak_core_util:rpc_every_member_ann(riak_kv_entropy_manager, disable, [], > 60000). > > and enable with the similar: > >> riak_core_util:rpc_every_member_ann(riak_kv_entropy_manager, enable, [], > 60000). > > That last number is just a timeout for the RPC operation. I hope this > saves you some extra load on your clusters. > > (3) That’s going to be : > (3a) List all keys using the client of your choice > (3b) Fetch each object > > https://www.tiot.jp/riak-docs/riak/kv/2.2.3/developing/usage/reading-objects/ > > https://www.tiot.jp/riak-docs/riak/kv/2.2.3/developing/usage/secondary-indexes/ > > > > > > > > On 19 Sep 2017, at 18:31, Leo <scicompl...@gmail.com> wrote: > > Dear Riak users and experts, > > I really appreciate any help with my questions below. > > I have a 3 node Riak cluster with each having approx. 1 TB disk usage. > All of a sudden, one node's hard disk failed unrecoverably. So, I > added a new node using the following steps: > > 1) riak-admin cluster join 2) down the failed node 3) riak-admin > force-replace failed-node new-node 4) riak-admin cluster plan 5) > riak-admin cluster commit. > > This almost fixed the problem except that after lots of data transfers > and handoffs, now not all three nodes have 1 TB disk usage. Only two > of them have 1 TB disk usage. The other one is almost empty (few 10s > of GBs). This means there are no longer 3 copies on disk anymore. My > data is completely random (no two keys have same data associated with > them. So, compression of data cannot be the reason for less data on > disk), > > I also tried using the "riak-admin cluster replace failednode newnode" > command so that the leaving node handsoff data to the joining node. > This however is not helpful if the leaving node has a failed hard > disk. I want the remaining live vnodes to help the new node recreate > the lost data using their replica copies. > > I have three questions: > > 1) What commands should I run to forcefully make sure there are three > replicas on disk overall without waiting for read-repair or > anti-entropy to make three copies ? Bandwidth usage or CPU usage is > not a huge concern for me. > > 2) Also, I will be very grateful if someone lists the commands that I > can run using "riak attach" so that I can clear the AAE trees and > forcefully make sure all data has 3 copies. > > 3) I will be very thankful if someone helps me with the commands that > I should run to ensure that all data has 3 replicas on disk after the > disk failure (instead of just looking at the disk space usage in all > the nodes as hints)? > > Thanks, > Leo > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > > _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
