From derby-user-return-13637-apmail-db-derby-user-archive=db.apache.org@db.apache.org Fri May 27 00:44:03 2011 Return-Path: X-Original-To: apmail-db-derby-user-archive@www.apache.org Delivered-To: apmail-db-derby-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 67BE86529 for ; Fri, 27 May 2011 00:44:03 +0000 (UTC) Received: (qmail 1110 invoked by uid 500); 27 May 2011 00:44:02 -0000 Delivered-To: apmail-db-derby-user-archive@db.apache.org Received: (qmail 1080 invoked by uid 500); 27 May 2011 00:44:02 -0000 Mailing-List: contact derby-user-help@db.apache.org; run by ezmlm Precedence: bulk list-help: list-unsubscribe: List-Post: List-Id: Reply-To: "Derby Discussion" Delivered-To: mailing list derby-user@db.apache.org Received: (qmail 1073 invoked by uid 99); 27 May 2011 00:44:02 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 27 May 2011 00:44:02 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of twu@terracottatech.com designates 64.95.112.230 as permitted sender) Received: from [64.95.112.230] (HELO mail01.terracottatech.com) (64.95.112.230) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 27 May 2011 00:43:56 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by mail01.terracottatech.com (Postfix) with ESMTP id 221851258088 for ; Thu, 26 May 2011 17:43:34 -0700 (PDT) X-Virus-Scanned: amavisd-new at mail01.terracottatech.com Received: from mail01.terracottatech.com ([127.0.0.1]) by localhost (mail01.terracottatech.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pxfBuaMgVKSH for ; Thu, 26 May 2011 17:43:33 -0700 (PDT) Received: from [10.2.0.242] (173-164-241-177-SFBA.hfc.comcastbusiness.net [173.164.241.177]) by mail01.terracottatech.com (Postfix) with ESMTP id 8EACF1258086 for ; Thu, 26 May 2011 17:43:33 -0700 (PDT) From: Tim Wu Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-6--415184912 Subject: Re: Corrupted Derby DB Date: Thu, 26 May 2011 17:43:33 -0700 In-Reply-To: To: "Derby Discussion" References: <762CE096-3BCE-4A9D-ADFB-E57FAE7D0ADC@terracottatech.com> <6FC567EE-D540-4050-9E8A-CB234EDC65DA@terracottatech.com> Message-Id: X-Mailer: Apple Mail (2.1084) --Apple-Mail-6--415184912 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Hi Brett, The test just kills the java process, but that is a good point about = write cache. I'll add mention of the nature of the crash test to the = JIRA. Thanks, Tim Wu On May 26, 2011, at 5:38 PM, Brett Wooldridge wrote: > Tim, >=20 > Just a question, was this 'crash test' a power-off test? For example, = turning off the computer while Derby is running? >=20 > If so, you should probably read this article: >=20 > = http://www.jasonbrome.com/blog/archives/2004/04/03/writecache_enabled.html= >=20 > TL;DR, anyone who expects complete durability (non-corruption even = during power loss) should disable the write-cache on their hard-disk. = There is no doubt this will cut the write performance quite a bit. = Applications needing both complete durability and high-performance = should consider a controller with a battery-backed write-cache. >=20 > Brett >=20 --Apple-Mail-6--415184912 Content-Transfer-Encoding: 7bit Content-Type: text/html; charset=us-ascii Hi Brett,

The test just kills the java process, but that is a good point about write cache. I'll add mention of the nature of the crash test to the JIRA.

Thanks,
Tim Wu
On May 26, 2011, at 5:38 PM, Brett Wooldridge wrote:

Tim,

Just a question, was this 'crash test' a power-off test?  For example, turning off the computer while Derby is running?

If so, you should probably read this article:


TL;DR, anyone who expects complete durability (non-corruption even during power loss) should disable the write-cache on their hard-disk.  There is no doubt this will cut the write performance quite a bit.  Applications needing both complete durability and high-performance should consider a controller with a battery-backed write-cache.

Brett


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