incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Adrian Cockcroft <adrian.cockcr...@gmail.com>
Subject Re: Multi-DC Deployment
Date Tue, 19 Apr 2011 09:06:34 GMT
If you want to use local quorum for a distributed setup, it doesn't
make sense to have less than RF=3 local and remote. Three copies at
both ends will give you high availability. Only one copy of the data
is sent over the wide area link (with recent versions).

There is no need to use mirrored or RAID5 disk in each node in this
case, since you are using RAIN (N for nodes) to protect your data. So
the extra disk space to hold three copies at each end shouldn't be a
big deal. Netflix is using striped internal disks on EC2 nodes for
this.

Adrian

On Mon, Apr 18, 2011 at 11:16 PM, Terje Marthinussen
<tmarthinussen@gmail.com> wrote:
> Hum...
> Seems like it could be an idea in a case like this with a mode where result
> is always returned (if possible), but where a flay saying if the consistency
> level was met, or to what level it was met (number of nodes answering for
> instance).?
> Terje
>
> On Tue, Apr 19, 2011 at 1:13 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
>>
>> They will timeout until failure detector realizes the DC1 nodes are
>> down (~10 seconds). After that they will immediately return
>> UnavailableException until DC1 comes back up.
>>
>> On Mon, Apr 18, 2011 at 10:43 AM, Baskar Duraikannu
>> <baskar.duraikannu.db@gmail.com> wrote:
>> > We are planning to deploy Cassandra on two data centers.   Let us say
>> > that
>> > we went with three replicas with 2 being in one data center and last
>> > replica
>> > in 2nd Data center.
>> >
>> > What will happen to Quorum Reads and Writes when DC1 goes down (2 of 3
>> > replicas are unreachable)?  Will they timeout?
>> >
>> >
>> > Regards,
>> > Baskar
>>
>>
>>
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of DataStax, the source for professional Cassandra support
>> http://www.datastax.com
>
>

Mime
View raw message