So if a RS goes down, it's assumed you lost the data on it, right? HBase has replications on HDFS, so if a RS goes down it doesn't mean I lost all the data, as I could have the replicas yet... But what happens if all RS hosting a specific region goes down? What if one RS from this one comes back again, but with the disk intact, with all the data it had before crashing?
From: user@hbase.apache.org Subject: Re: write availability When a RS goes down, the Master will try to assign the regions on the remaining RSes. When the RS comes back, after a while, the Master balancer process will re-distribute regions between RS, so the given RS will be hosting regions, but not necessarily the one it used to host before it went down. On 7 Apr 2015, at 16:31, Marcelo Valle (BLOOMBERG/ LONDON) <mvallemil...@bloomberg.net> wrote: >> So if the cluster is up, then you can insert records in to HBase even though >> you lost a RS that was handing a specific region. > > What happens when the RS goes down? Writes to that region will be written to > another region server? Another RS assumes the region "range" while the RS is > down? > > What happens when the RS that was down goes up again? > > > From: user@hbase.apache.org > Subject: Re: write availability > > I don’t know if I would say that… > > I read Marcelo’s question of “if the cluster is up, even though a RS may be > down, can I still insert records in to HBase?” > > So if the cluster is up, then you can insert records in to HBase even though > you lost a RS that was handing a specific region. > > But because he talked about syncing nodes… I could be misreading his initial > question… > >> On Apr 7, 2015, at 9:02 AM, Serega Sheypak <serega.shey...@gmail.com> wrote: >> >>> If I have an application that writes to a HBase cluster, can I count that >> the cluster will always available to receive writes? >> No, it's CP, not AP system. >>> so everything get in sync when the other nodes get up again >> There is no hinted backoff, It's not Cassandra. >> >> >> >> 2015-04-07 14:48 GMT+02:00 Marcelo Valle (BLOOMBERG/ LONDON) < >> mvallemil...@bloomberg.net>: >> >>> If I have an application that writes to a HBase cluster, can I count that >>> the cluster will always available to receive writes? >>> I might not be able to read if a region server which handles a range of >>> keys is down, but will I be able to keep writing to other nodes, so >>> everything get in sync when the other nodes get up again? >>> Or I might get no write availability for a while? > > The opinions expressed here are mine, while they may reflect a cognitive > thought, that is purely accidental. > Use at your own risk. > Michael Segel > michael_segel (AT) hotmail.com
