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Posted to dev@cassandra.apache.org by Ted Zlatanov <tz...@lifelogs.com> on 2010/02/25 16:17:21 UTC

Re: consistent backups

On Thu, 25 Feb 2010 08:22:38 -0600 Jonathan Ellis <jb...@gmail.com> wrote: 

JE> 2010/2/25 Ted Zlatanov <tz...@lifelogs.com>:
>> I want a consistent backup.

JE> You can get an "eventually consistent backup" by flushing all nodes
JE> and snapshotting; no individual node's backup is guaranteed to be
JE> consistent but if you restore from that snapshot then clients will get
JE> eventually consistent behavior as usual.

JE> Other than that there is no such thing as a "consistent view of the
JE> data" in the strict sense, except in the trivial case of writes with
JE> CL.ALL.

That makes perfect sense, thanks for explaining.  Can the explanation be
part of the http://wiki.apache.org/cassandra/Operations section on
backups?  I'll submit the edit if you want.

Thanks
Ted

Re: consistent backups

Posted by Jonathan Ellis <jb...@gmail.com>.

Go ahead.

2010/2/25 Ted Zlatanov <tz...@lifelogs.com>:
> On Thu, 25 Feb 2010 08:22:38 -0600 Jonathan Ellis <jb...@gmail.com> wrote:
>
> JE> 2010/2/25 Ted Zlatanov <tz...@lifelogs.com>:
>>> I want a consistent backup.
>
> JE> You can get an "eventually consistent backup" by flushing all nodes
> JE> and snapshotting; no individual node's backup is guaranteed to be
> JE> consistent but if you restore from that snapshot then clients will get
> JE> eventually consistent behavior as usual.
>
> JE> Other than that there is no such thing as a "consistent view of the
> JE> data" in the strict sense, except in the trivial case of writes with
> JE> CL.ALL.
>
> That makes perfect sense, thanks for explaining.  Can the explanation be
> part of the http://wiki.apache.org/cassandra/Operations section on
> backups?  I'll submit the edit if you want.
>
> Thanks
> Ted
>
>