Tom Lane wrote: > Adrian Klaver <aklaver@xxxxxxxxxxx> writes: >> Nothing. I have created a Postgres instance on an EC2 virtual machine with >> attached EBS(Elastic Block Storage)..[...] > > ... I wonder whether you have any guarantees about database consistency > in that situation? PG has some pretty strong requirements about fsync While I agree it shouldn't be taken on faith, their documentation does take the time to point out that syncing of I/O's is pretty expensive operation (even literally - they charge extra for individual i/o operations and point out that those increase with syncs). http://aws.amazon.com/ebs/ I have a couple databases there, and based on the rather high I/O-wait times on their cheapest ($0.10/hr) instances, I'm wildly guessing that they're doing something reasonable for sync :-). Their higher priced instances supposedly have better I/O performance. > behavior etc, and I'd not want to take it on faith that a cloud > environment will meet those requirements. That said, even apart from any SLA of fsync itself, I imagine there's a concern that an entire hosted cloud might vanish for any number of reasons. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
