You are viewing a plain text version of this content. The canonical link for it is here.
Posted to common-user@hadoop.apache.org by edward choi <mp...@gmail.com> on 2011/10/12 11:34:39 UTC
Does Hbase automatically restore data when regionservers fail?
Hi,
I am using CDH3U0 Hadoop and Hbase.
I know that HDFS automatically replicates data to multiple data nodes so
that when a couple of data nodes fail, the user won't lose any data.
I am currently using replication factor of 3.
Now in Hbase, I know there is some experimental replication service, but I
am not using it. I thought that since HDFS already does replication, Hbase
wouldn't need additional replication.
Am I right on this?
So my question would be:
Given that I am using HDFS replication and not using Hbase replication, if a
couple of regionservers fail, am I still able to access all the data I have
stored before?
I would appreciate any help.
Thanks.
Ed
Re: Does Hbase automatically restore data when regionservers fail?
Posted by bijieshan <bi...@huawei.com>.
The precondition is that you should not disabled the WAL. Otherwise, the newly written data may get lost.
Regards,
Jieshan
-----Original Message-----
Hi,
I am using CDH3U0 Hadoop and Hbase.
I know that HDFS automatically replicates data to multiple data nodes so
that when a couple of data nodes fail, the user won't lose any data.
I am currently using replication factor of 3.
Now in Hbase, I know there is some experimental replication service, but I
am not using it. I thought that since HDFS already does replication, Hbase
wouldn't need additional replication.
Am I right on this?
So my question would be:
Given that I am using HDFS replication and not using Hbase replication, if a
couple of regionservers fail, am I still able to access all the data I have
stored before?
I would appreciate any help.
Thanks.
Ed
Re: Does Hbase automatically restore data when regionservers fail?
Posted by edward choi <mp...@gmail.com>.
Oh, my mistake on the last question. I was still confused about the concept
of Hbase replication service.
Scratch my last question.
Ed
2011/10/13 edward choi <mp...@gmail.com>
>
> Thank you all for the reply.
>
> Good thing to know that Hbase automatically restores data when
> regionservers fail.
> That is, even when I don't use Hbase replication service right?
>
> And sorry about posting to two lists at the same time. I thought since the
> question also relates to HDFS, I'd post to Hadoop list too.
>
> Regards,
> Ed
>
> 2011/10/12 Harsh J <ha...@cloudera.com>
>
>> Edward,
>>
>> HBase replication is entirely different than HDFS replication - The
>> former being cross-instance replication of HBase-data-only while the
>> latter replicates within nodes available in its own instance, and
>> covers all data generally.
>>
>> Read more about it here: http://hbase.apache.org/replication.html and
>> decide for yourself if you'd like to use it.
>>
>> (P.s. Please do not cross post to multiple lists. This question fit
>> HBase's lists.)
>>
>> On Wed, Oct 12, 2011 at 3:04 PM, edward choi <mp...@gmail.com> wrote:
>> > Hi,
>> >
>> > I am using CDH3U0 Hadoop and Hbase.
>> >
>> > I know that HDFS automatically replicates data to multiple data nodes so
>> > that when a couple of data nodes fail, the user won't lose any data.
>> > I am currently using replication factor of 3.
>> >
>> > Now in Hbase, I know there is some experimental replication service, but
>> I
>> > am not using it. I thought that since HDFS already does replication,
>> Hbase
>> > wouldn't need additional replication.
>> > Am I right on this?
>> >
>> > So my question would be:
>> > Given that I am using HDFS replication and not using Hbase replication,
>> if a
>> > couple of regionservers fail, am I still able to access all the data I
>> have
>> > stored before?
>> >
>> > I would appreciate any help.
>> > Thanks.
>> >
>> > Ed
>> >
>>
>>
>>
>> --
>> Harsh J
>>
>
>
Re: Does Hbase automatically restore data when regionservers fail?
Posted by edward choi <mp...@gmail.com>.
Thank you all for the reply.
Good thing to know that Hbase automatically restores data when regionservers
fail.
That is, even when I don't use Hbase replication service right?
And sorry about posting to two lists at the same time. I thought since the
question also relates to HDFS, I'd post to Hadoop list too.
Regards,
Ed
2011/10/12 Harsh J <ha...@cloudera.com>
> Edward,
>
> HBase replication is entirely different than HDFS replication - The
> former being cross-instance replication of HBase-data-only while the
> latter replicates within nodes available in its own instance, and
> covers all data generally.
>
> Read more about it here: http://hbase.apache.org/replication.html and
> decide for yourself if you'd like to use it.
>
> (P.s. Please do not cross post to multiple lists. This question fit
> HBase's lists.)
>
> On Wed, Oct 12, 2011 at 3:04 PM, edward choi <mp...@gmail.com> wrote:
> > Hi,
> >
> > I am using CDH3U0 Hadoop and Hbase.
> >
> > I know that HDFS automatically replicates data to multiple data nodes so
> > that when a couple of data nodes fail, the user won't lose any data.
> > I am currently using replication factor of 3.
> >
> > Now in Hbase, I know there is some experimental replication service, but
> I
> > am not using it. I thought that since HDFS already does replication,
> Hbase
> > wouldn't need additional replication.
> > Am I right on this?
> >
> > So my question would be:
> > Given that I am using HDFS replication and not using Hbase replication,
> if a
> > couple of regionservers fail, am I still able to access all the data I
> have
> > stored before?
> >
> > I would appreciate any help.
> > Thanks.
> >
> > Ed
> >
>
>
>
> --
> Harsh J
>
Re: Does Hbase automatically restore data when regionservers fail?
Posted by Harsh J <ha...@cloudera.com>.
Edward,
HBase replication is entirely different than HDFS replication - The
former being cross-instance replication of HBase-data-only while the
latter replicates within nodes available in its own instance, and
covers all data generally.
Read more about it here: http://hbase.apache.org/replication.html and
decide for yourself if you'd like to use it.
(P.s. Please do not cross post to multiple lists. This question fit
HBase's lists.)
On Wed, Oct 12, 2011 at 3:04 PM, edward choi <mp...@gmail.com> wrote:
> Hi,
>
> I am using CDH3U0 Hadoop and Hbase.
>
> I know that HDFS automatically replicates data to multiple data nodes so
> that when a couple of data nodes fail, the user won't lose any data.
> I am currently using replication factor of 3.
>
> Now in Hbase, I know there is some experimental replication service, but I
> am not using it. I thought that since HDFS already does replication, Hbase
> wouldn't need additional replication.
> Am I right on this?
>
> So my question would be:
> Given that I am using HDFS replication and not using Hbase replication, if a
> couple of regionservers fail, am I still able to access all the data I have
> stored before?
>
> I would appreciate any help.
> Thanks.
>
> Ed
>
--
Harsh J