Hi Vitaly,

When a transaction commits, the data has been written to several disks in a
single datacenter. Thus, no one hardware failure can cause data to be lost.
Shortly thereafter, your data is replicated to other locations, providing
security against anything that affects a whole location. In theory, you
could lose data if something really drastic happened to a datacenter
immediately after a write but before replication - but this is extremely
unlikely!

If you're worried about unnoticed dataloss, I can assure you this is not
possible - if data is lost, we would be fully aware of it, and taking steps
to recover it if possible.

-Nick Johnson

On Sun, Aug 22, 2010 at 10:08 AM, Vitaly <[email protected]> wrote:

> Hi,
>
> Can I be sure that data in App Engine's datastore will not be lost
> after successful transaction commit? Is it possible that some recent
> changes to database will be lost if hardware failure occurs before
> replication to another datastore server is finished?
>
> Thanks,
>    Vitaly
>
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-- 
Nick Johnson, Developer Programs Engineer, App Engine Google Ireland Ltd. ::
Registered in Dublin, Ireland, Registration Number: 368047
Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number:
368047

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