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HBase >> mail # dev >> [question about replication] how to apply delta from Master to Slave after crash ?


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Re: [question about replication] how to apply delta from Master to Slave after crash ?
It's not possible right now to copy the delta if your cluster is down,
but since replication only uses the HLogs, as long as you can keep ZK
running (to know what needs to be replicated) it should be possible to
write a small tool that will finish replicating what's missing.

That could be a nice tool to have in HBase. Would it work for you?

J-D
On Fri, Jul 26, 2013 at 10:44 AM, Demai Ni <[EMAIL PROTECTED]> wrote:
> JD,
>
> thanks. I agree with you. the current replication mechanism will handle
> such situation exactly as you suggested.  Were I the DBA, I will focus on
> restart my Master-cluster instead of shipping the delta over to
> slave-cluster.
>
> However, my customer still would like to have the tool to sync-up the data
> in the case of Master down. I guess the reasons are not purely from
> technical perspective, more for a business check mark. :-(
>
> that is why I am looking for a way. Can you please give me some pointers to
> start with? many thanks
>
> Demai
>
>
> On Fri, Jul 26, 2013 at 10:08 AM, Jean-Daniel Cryans <[EMAIL PROTECTED]>wrote:
>
>> As soon as you restart your master, it will continue replicating from
>> where it was, so it will send that delta.
>>
>> J-D
>>
>> On Mon, Jul 22, 2013 at 4:42 PM, Demai Ni <[EMAIL PROTECTED]> wrote:
>> > hi, folks,
>> >
>> > I am trying to address a recovery scenario after Master crash.
>> >
>> > In a simple Master - Slave replication setup for t1, and suddenly Master
>> > crashes. there will be a small delta of t1 already changed on Master, but
>> > haven't been replicated to Slave yet.  Assuming Master's filesystem and
>> > network still available, how to apply the delta from Master to Slave to
>> > sync t1.
>> >
>> > Anyone addresses this scenario in your shop? Can you please give me some
>> > pointers?
>> >
>> > Basically, I need to address two things:
>> > 1) get the timestamp of last consistent point of T1. some thing like
>> > oldest(lastAppliedOP_of_T1 of each regionServer on Slave Cluster).  Any
>> > other way to do so?
>> >
>> > 2) something like copyTable utility with starttime from 1). However
>> > copyTable requests hbase and zookeep available from source
>> cluster(right?)
>> >
>> >
>> > I have been thinking about ways to address this for quite a few days and
>> > still don't have very good ideas yet. Any suggestion is greatly
>> appreciated
>> >
>> > thanks.
>> >
>> > Demai
>>