From mbenne@m-bass.com Wed Aug 29 19:29:07 2007 Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 1A2F69FB6FC for ; Wed, 29 Aug 2007 16:29:07 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 74142-03 for ; Wed, 29 Aug 2007 16:28:46 -0300 (ADT) X-Greylist: delayed 00:06:38.299611 by SQLgrey-1.7.5 Received: from web31601.mail.mud.yahoo.com (web31601.mail.mud.yahoo.com [68.142.198.147]) by postgresql.org (Postfix) with SMTP id A3D729FB6BA for ; Wed, 29 Aug 2007 16:28:48 -0300 (ADT) Received: (qmail 65210 invoked by uid 60001); 29 Aug 2007 19:22:03 -0000 X-YMail-OSG: NCwAZWsVM1lgRiUtX0eLZyGM.Hgagf02xrgp7wO8kNpv9pHmFBsv5jQ0tQjr.P.4LpNdTecUQw-- Received: from [68.142.201.149] by web31601.mail.mud.yahoo.com via HTTP; Wed, 29 Aug 2007 12:22:03 PDT X-Mailer: YahooMailRC/651.50 YahooMailWebService/0.7.134 Date: Wed, 29 Aug 2007 12:22:03 -0700 (PDT) From: Markus Benne Subject: Transaction Log To: pgsql-performance@postgresql.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-17621483-1188415323=:64168" Message-ID: <464321.64168.qm@web31601.mail.mud.yahoo.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.002 tagged_above=0 required=5 tests=BAYES_50=0.001, HTML_MESSAGE=0.001 X-Spam-Level: X-Archive-Number: 200708/384 X-Sequence-Number: 26514 --0-17621483-1188415323=:64168 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable For best performance, the transaction log should be on a separate disk.=0A= =0ADoes the writing of the log benefit from a battery backed controller as = well? If not, what do people think about writing the transaction log to a = flash card or the like?=0A=0A --0-17621483-1188415323=:64168 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable
For best performance, the transaction log should be on a separate d= isk.

Does the writing of the log benefit from a battery backed contr= oller as well?  If not, what do people think about writing the transac= tion log to a flash card or the like?
--0-17621483-1188415323=:64168-- From mbguy2000-1@yahoo.com Wed Aug 29 19:31:20 2007 Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 87C0B9FB63E for ; Wed, 29 Aug 2007 16:31:20 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 82964-02-3 for ; Wed, 29 Aug 2007 16:31:14 -0300 (ADT) X-Greylist: delayed 00:06:39.744817 by SQLgrey-1.7.5 Received: from web31603.mail.mud.yahoo.com (web31603.mail.mud.yahoo.com [68.142.198.149]) by postgresql.org (Postfix) with SMTP id 7AD4A9F981A for ; Wed, 29 Aug 2007 16:31:16 -0300 (ADT) Received: (qmail 73363 invoked by uid 60001); 29 Aug 2007 19:24:34 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type:Message-ID; b=qqgmz/5N7yRHiZMGg5WyyKl5dj4zTl+pTVBULdiStRj1BLbUEKQN3vm+//8bRSDrkJjogxk7iaPvavYI5gNlULkVGr415JJRscveBQdPIa9lm9UVgXL6a1grYtcqX4/joAR3vdrSpK8XsQe6YDTpvN/91iLarFeVSt5oWJbihmY=; X-YMail-OSG: AaPZGWcVM1lUddcvQgQxxMYYy0yu5RsU6xFv_qcAfWabFglNr1ancZn7wekoCQ5i3A-- Received: from [68.142.201.149] by web31603.mail.mud.yahoo.com via HTTP; Wed, 29 Aug 2007 12:24:34 PDT X-Mailer: YahooMailRC/651.50 YahooMailWebService/0.7.134 Date: Wed, 29 Aug 2007 12:24:34 -0700 (PDT) From: mbguy2000-1@yahoo.com Subject: Transaction Log To: pgsql-performance@postgresql.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1994608125-1188415474=:73151" Message-ID: <782718.73151.qm@web31603.mail.mud.yahoo.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.002 tagged_above=0 required=5 tests=BAYES_50=0.001, HTML_MESSAGE=0.001 X-Spam-Level: X-Archive-Number: 200708/383 X-Sequence-Number: 26513 --0-1994608125-1188415474=:73151 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable For best performance, the transaction log should be on a separate disk.=0A= =0ADoes=0Athe writing of the log benefit from a battery backed controller a= s=0Awell? If not, what do people think about writing the transaction log= =0Ato a flash card or the like?=0A --0-1994608125-1188415474=:73151 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable
For best performance, the transaction log should be on a separate d= isk.

Does=0Athe writing of the log benefit from a battery backed con= troller as=0Awell?  If not, what do people think about writing the tra= nsaction log=0Ato a flash card or the like?
--0-1994608125-1188415474=:73151-- From mark@mark.mielke.cc Wed Aug 29 19:54:19 2007 Received: from localhost (maia-5.hub.org [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id DCB3F9FA4DF for ; Wed, 29 Aug 2007 16:54:19 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 24807-04 for ; Wed, 29 Aug 2007 16:54:08 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from ironport2-out.pppoe.ca (ironport2-out.pppoe.ca [206.248.154.182]) by postgresql.org (Postfix) with ESMTP id 9A6E99F9C3B for ; Wed, 29 Aug 2007 16:54:07 -0300 (ADT) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ao8CADps1UbO+Igp/2dsb2JhbACCbQ X-IronPort-AV: E=Sophos;i="4.19,323,1183348800"; d="scan'208,217";a="5770571" Received: from smtp.pppoe.ca ([65.39.196.238]) by ironport2-out.pppoe.ca with ESMTP; 29 Aug 2007 15:54:06 -0400 Received: from [206.248.136.41] ([206.248.136.41]) by smtp.pppoe.ca (Internet Mail Server v1.0) with ESMTP id IBF33206; Wed, 29 Aug 2007 15:54:06 -0400 Message-ID: <46D5CEDD.5010303@mark.mielke.cc> Date: Wed, 29 Aug 2007 15:54:05 -0400 From: Mark Mielke User-Agent: Thunderbird 2.0.0.5 (X11/20070719) MIME-Version: 1.0 To: mbguy2000-1@yahoo.com CC: pgsql-performance@postgresql.org Subject: Re: Transaction Log References: <782718.73151.qm@web31603.mail.mud.yahoo.com> In-Reply-To: <782718.73151.qm@web31603.mail.mud.yahoo.com> Content-Type: multipart/alternative; boundary="------------090103070607010707070905" X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/385 X-Sequence-Number: 26515 This is a multi-part message in MIME format. --------------090103070607010707070905 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit mbguy2000-1@yahoo.com wrote: > For best performance, the transaction log should be on a separate disk. > > Does the writing of the log benefit from a battery backed controller > as well? If not, what do people think about writing the transaction > log to a flash card or the like? How popular are the battery backed RAM drives that exist today? I don't recall seeing them spoken about in this mailing list. The local geek shop has these devices on sale. Are they still too expensive? For those that don't know what I am talking about - they are PCI devices that present themselves as a hard drive, but are filled with commodity RAM instead of a magnetic platter, and a battery that lasts a few weeks without external power. Cheers, mark -- Mark Mielke --------------090103070607010707070905 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit mbguy2000-1@yahoo.com wrote:
For best performance, the transaction log should be on a separate disk.

Does the writing of the log benefit from a battery backed controller as well?  If not, what do people think about writing the transaction log to a flash card or the like?
How popular are the battery backed RAM drives that exist today? I don't recall seeing them spoken about in this mailing list. The local geek shop has these devices on sale. Are they still too expensive?

For those that don't know what I am talking about - they are PCI devices that present themselves as a hard drive, but are filled with commodity RAM instead of a magnetic platter, and a battery that lasts a few weeks without external power.

Cheers,
mark

-- 
Mark Mielke <mark@mielke.cc>
--------------090103070607010707070905-- From steve@blighty.com Wed Aug 29 20:11:44 2007 Received: from localhost (maia-5.hub.org [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id DC3B29F9D04 for ; Wed, 29 Aug 2007 17:11:44 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 36680-04 for ; Wed, 29 Aug 2007 17:11:35 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from m.wordtothewise.com (fruitbat.wordtothewise.com [208.187.80.135]) by postgresql.org (Postfix) with ESMTP id E35009F959B for ; Wed, 29 Aug 2007 17:11:36 -0300 (ADT) Received: from [10.3.2.34] (184.wordtothewise.com [208.187.80.184]) by m.wordtothewise.com (Postfix) with ESMTP id 9230B800C3 for ; Wed, 29 Aug 2007 13:11:35 -0700 (PDT) Mime-Version: 1.0 (Apple Message framework v752.3) In-Reply-To: <46D5CEDD.5010303@mark.mielke.cc> References: <782718.73151.qm@web31603.mail.mud.yahoo.com> <46D5CEDD.5010303@mark.mielke.cc> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Steve Atkins Subject: Re: Transaction Log Date: Wed, 29 Aug 2007 13:11:32 -0700 To: PostgreSQL Performance X-Mailer: Apple Mail (2.752.3) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/386 X-Sequence-Number: 26516 On Aug 29, 2007, at 12:54 PM, Mark Mielke wrote: > mbguy2000-1@yahoo.com wrote: >> For best performance, the transaction log should be on a separate >> disk. >> >> Does the writing of the log benefit from a battery backed >> controller as well? If not, what do people think about writing >> the transaction log to a flash card or the like? > How popular are the battery backed RAM drives that exist today? I > don't recall seeing them spoken about in this mailing list. The > local geek shop has these devices on sale. Are they still too > expensive? > > For those that don't know what I am talking about - they are PCI > devices that present themselves as a hard drive, but are filled > with commodity RAM instead of a magnetic platter, and a battery > that lasts a few weeks without external power. It think the general conclusion was "When they come out with an ECC version, we'll look at them." There are higher end ones that do have ECC RAM (and backup drives and stuff) but they're spectacularly more expensive than the cheapo consumer ones. Cheers, Steve From sgunderson@bigfoot.com Wed Aug 29 20:18:05 2007 Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 2C5D29FA505 for ; Wed, 29 Aug 2007 17:18:05 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 11808-07 for ; Wed, 29 Aug 2007 17:17:58 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from cassarossa.samfundet.no (cassarossa.samfundet.no [129.241.93.19]) by postgresql.org (Postfix) with ESMTP id 8538E9FA500 for ; Wed, 29 Aug 2007 17:18:01 -0300 (ADT) Received: from trofast.ipv6.sesse.net ([2001:700:300:1803:20e:cff:fe36:a766] helo=trofast.sesse.net) by cassarossa.samfundet.no with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from ) id 1IQTzC-0006OS-Q6 for pgsql-performance@postgresql.org; Wed, 29 Aug 2007 22:17:59 +0200 Received: from root by trofast.sesse.net with local (Exim 4.67) (envelope-from ) id 1IQTzC-000522-3f for pgsql-performance@postgresql.org; Wed, 29 Aug 2007 22:17:58 +0200 Date: Wed, 29 Aug 2007 22:17:58 +0200 From: "Steinar H. Gunderson" To: pgsql-performance@postgresql.org Subject: Re: Transaction Log Message-ID: <20070829201757.GA19275@uio.no> Mail-Followup-To: pgsql-performance@postgresql.org References: <782718.73151.qm@web31603.mail.mud.yahoo.com> <46D5CEDD.5010303@mark.mielke.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Operating-System: Linux 2.6.20.4 on a x86_64 X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ User-Agent: Mutt/1.5.16 (2007-06-11) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/387 X-Sequence-Number: 26517 On Wed, Aug 29, 2007 at 01:11:32PM -0700, Steve Atkins wrote: > It think the general conclusion was "When they come out with an ECC > version, we'll look at them." FWIW, it shouldn't be impossible to implement ECC in software; they'd still be orders of magnitude faster than normal disks. /* Steinar */ -- Homepage: http://www.sesse.net/ From wmoran@collaborativefusion.com Wed Aug 29 20:22:04 2007 Received: from localhost (maia-5.hub.org [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id F35B69FA5C0 for ; Wed, 29 Aug 2007 17:22:04 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 43279-09 for ; Wed, 29 Aug 2007 17:21:55 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from mx00.pub.collaborativefusion.com (mx00.pub.collaborativefusion.com [206.210.89.199]) by postgresql.org (Postfix) with ESMTP id 122BB9FA527 for ; Wed, 29 Aug 2007 17:21:57 -0300 (ADT) Received: from vanquish.pitbpa0.priv.collaborativefusion.com (vanquish.pitbpa0.priv.collaborativefusion.com [192.168.2.61]) (SSL: TLSv1/SSLv3,256bits,AES256-SHA) by wingspan with esmtp; Wed, 29 Aug 2007 16:21:53 -0400 id 00056417.46D5D562.00005BC8 Date: Wed, 29 Aug 2007 16:21:53 -0400 From: Bill Moran To: Mark Mielke Cc: mbguy2000-1@yahoo.com, pgsql-performance@postgresql.org Subject: Re: Transaction Log Message-Id: <20070829162153.cc48bced.wmoran@collaborativefusion.com> In-Reply-To: <46D5CEDD.5010303@mark.mielke.cc> References: <782718.73151.qm@web31603.mail.mud.yahoo.com> <46D5CEDD.5010303@mark.mielke.cc> Organization: Collaborative Fusion X-Mailer: Sylpheed 2.4.4 (GTK+ 2.10.14; i386-portbld-freebsd6.2) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/388 X-Sequence-Number: 26518 In response to Mark Mielke : > mbguy2000-1@yahoo.com wrote: > > For best performance, the transaction log should be on a separate disk. > > > > Does the writing of the log benefit from a battery backed controller > > as well? If not, what do people think about writing the transaction > > log to a flash card or the like? Flash cards write _very_ slowly. > How popular are the battery backed RAM drives that exist today? I don't > recall seeing them spoken about in this mailing list. The local geek > shop has these devices on sale. Are they still too expensive? I've seen them around and as best I can tell, they're pretty inexpensive. The main drawback is the storage, you'd be looking at the price of the card, plus the price of however much RAM you wanted on it. http://www.amazon.com/Gigabyte-GC-RAMDISK-i-RAM-Hard-Drive/dp/B000EPM9NC/ref=pd_bbs_sr_1/102-3968336-1618519?ie=UTF8&s=electronics&qid=1188418613&sr=8-1 http://techreport.com/articles.x/9312/1 Up to 4G, but you have to add the price of the RAM on to the price of the card. In the case of WAL logs, you could probably get away with a lot less space than many other usages, so they might be very practical. -- Bill Moran Collaborative Fusion Inc. http://people.collaborativefusion.com/~wmoran/ wmoran@collaborativefusion.com Phone: 412-422-3463x4023 From ahodgson@simkin.ca Wed Aug 29 20:37:06 2007 Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id C00479FB272 for ; Wed, 29 Aug 2007 17:37:06 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 36834-03 for ; Wed, 29 Aug 2007 17:36:59 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from skynet.simkin.ca (skynet.simkin.ca [72.51.27.117]) by postgresql.org (Postfix) with ESMTP id 638939FA489 for ; Wed, 29 Aug 2007 17:37:03 -0300 (ADT) Received: from charon.medialogik.com (charon.medialogik.com [72.51.27.114]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by skynet.simkin.ca (Postfix) with ESMTP id 9E8354A54 for ; Wed, 29 Aug 2007 13:36:59 -0700 (PDT) From: Alan Hodgson Organization: Simkin Network Consulting To: pgsql-performance@postgresql.org Subject: Re: Transaction Log Date: Wed, 29 Aug 2007 13:36:48 -0700 User-Agent: KMail/1.9.6 References: <782718.73151.qm@web31603.mail.mud.yahoo.com> <46D5CEDD.5010303@mark.mielke.cc> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200708291336.48730@hal.medialogik.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/389 X-Sequence-Number: 26519 On Wednesday 29 August 2007, Steve Atkins wrote: > There are higher end ones that do have ECC RAM (and backup drives and > stuff) but they're spectacularly more expensive than the cheapo > consumer ones. > Yeah the good ones look more like http://ramsan.com/ . -- "Pulling together is the aim of despotism and tyranny. Free men pull in all kinds of directions." -- Terry Pratchett