Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id ECFD51337B83 for ; Thu, 23 Dec 2010 21:01:08 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 68622-03 for ; Fri, 24 Dec 2010 01:01:02 +0000 (UTC) X-Greylist: delayed 00:11:40.573077 by SQLgrey-1.7.6 Received: from mx1.fusionio.com (mx1.fusionio.com [64.244.102.30]) by mail.postgresql.org (Postfix) with ESMTP id 87D581337B7E for ; Thu, 23 Dec 2010 21:01:00 -0400 (AST) X-ASG-Debug-ID: 1293151758-1789a5b90001-c4zXsc Received: from mail1.int.fusionio.com (mail1.int.fusionio.com [10.101.1.21]) by mx1.fusionio.com with ESMTP id yAF00OZchQwBaH9h; Thu, 23 Dec 2010 17:49:18 -0700 (MST) X-Barracuda-Envelope-From: JCagle@fusionio.com Received: from mbx.int.fusionio.com ([fe80::eda1:b76:26ed:5fdf]) by mail1.int.fusionio.com ([fe80::7ca4:b3f2:c334:44ea%11]) with mapi; Thu, 23 Dec 2010 17:49:17 -0700 From: John Cagle X-Barracuda-Apparent-Source-IP: fe80::eda1:b76:26ed:5fdf To: "angelflow@yahoo.com" CC: "wozniak@lanl.gov" , "pgsql-performance@postgresql.org" , "john.w.strange@jpmchase.com" Date: Thu, 23 Dec 2010 17:49:16 -0700 Subject: Re: concurrent IO in postgres? Thread-Topic: concurrent IO in postgres? X-ASG-Orig-Subj: Re: concurrent IO in postgres? Thread-Index: AcujBGRDyZAv83JgSp2vj/ljmrlHMQ== Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.2.0.101115 acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1293151758 X-Barracuda-URL: http://10.101.1.180:8000/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at fusionio.com X-Barracuda-Bayes: INNOCENT GLOBAL 0.4814 1.0000 0.0000 X-Barracuda-Spam-Score: 0.96 X-Barracuda-Spam-Status: No, SCORE=0.96 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests=GUARANTEED_100_PERCENT X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.50311 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 0.96 GUARANTEED_100_PERCENT BODY: One hundred percent guaranteed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.789 tagged_above=-10 required=5 tests=BAYES_00=-1.9, GUARANTEED_100_PERCENT=2.699, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201012/304 X-Sequence-Number: 41756 On Dec 23, 2010, at 13:22:32, Ben Chobot wrote: >=20 > 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? >=20 > 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 attachmen= ts to it are confidential to the intended recipient, and may contain inform= ation that is privileged and/or exempt from disclosure under applicable law= . If you are not the intended recipient, please immediately notify the send= er and destroy the original e-mail message and any attachments (and any cop= ies that may have been made) from your system or otherwise. Any unauthorize= d use, copying, disclosure or distribution of this information is strictly = prohibited.