On Dec 23, 2010, at 13:22:32, Ben Chobot wrote: > > On Dec 23, 2010, at 11:58 AM, Andy wrote: > > > > Somewhat tangential to the current topics, I've heard that FusionIO >uses > > internal cache and hence is not crash-safe, and if the cache is turned > > off performance will take a big hit. Is that your experience? > > It does use an internal cache, but it also has onboard battery power. The > driver needs to put its house in order when restarting after an unclean > shutdown, however, and that can take up to 30 minutes per card. Sorry to intrude here, but I'd like to clarify the behavior of the Fusion-io devices. Unlike SSDs, we do not use an internal cache nor do we use batteries. (We *do* have a small internal FIFO (with capacitive hold-up) that is 100% guaranteed to be written to our persistent storage in the event of unexpected power failure.) When a write() to a Fusion-io device has been acknowledged, the data is guaranteed to be stored safely. This is a strict requirement for any enterprise-ready storage device. Thanks, John Cagle Fusion-io, Inc. Confidentiality Notice: This e-mail message, its contents and any attachments to it are confidential to the intended recipient, and may contain information that is privileged and/or exempt from disclosure under applicable law. If you are not the intended recipient, please immediately notify the sender and destroy the original e-mail message and any attachments (and any copies that may have been made) from your system or otherwise. Any unauthorized use, copying, disclosure or distribution of this information is strictly prohibited. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
