Received: from localhost (unknown [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id 8F2A62E3DFB for ; Fri, 18 Jan 2008 15:35:24 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 40801-07 for ; Fri, 18 Jan 2008 15:35:18 -0400 (AST) Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.176]) by postgresql.org (Postfix) with ESMTP id AE25B2E3A36 for ; Fri, 18 Jan 2008 15:35:18 -0400 (AST) Received: by wa-out-1112.google.com with SMTP id m38so2046697waf.5 for ; Fri, 18 Jan 2008 11:35:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:references:x-google-sender-auth; bh=6IyZyjDhN/aGTXmHTsyordUAY3Md0Xgeg6yDGqpfHEY=; b=V1DsXdTqYVA8AefWdqHESLQlfd02AMV2CraRNHTdVZ3493TLnJbuHN+dP1wwe9qwNDz4vESMnbUCIzsUZMc7sbDMd5DNqTekB8Byogw1x2hPx6BZXdw98+bxbLOmVYvwc+Xkcj2OXa8XECzZC2Fz7wv8btAAa5Z9kjtubc3kGbg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=GKnTm+V9fUKo+giD42MaAmFLg10zqZeqgxSorGGSe+Y8sehdsdZ+aFbOrP8tBMIB+iueiqmyPmFMKC7SrQxCfLyCphTTLmI1oA314BCSqORzPU4ZGa/YWB8t25559pMUm32oqnPKw5Mo/hpLhAiZ+d4yBL4tx3JmxE8kPCOFUAM= Received: by 10.114.94.1 with SMTP id r1mr1469797wab.32.1200684915771; Fri, 18 Jan 2008 11:35:15 -0800 (PST) Received: by 10.114.174.2 with HTTP; Fri, 18 Jan 2008 11:35:15 -0800 (PST) Message-ID: <264855a00801181135p693e4ceek7c4b2f506ca21e80@mail.gmail.com> Date: Fri, 18 Jan 2008 14:35:15 -0500 From: "Sean Davis" To: "Greg Smith" Subject: Re: [OT] RAID controllers blocking one another? Cc: pgsql-performance@postgresql.org In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_7682_20542695.1200684915769" References: <264855a00801171217m4e6211e6y5f4d0e12ce86db5c@mail.gmail.com> <264855a00801180503k14910362p3165b46e8450d045@mail.gmail.com> X-Google-Sender-Auth: 899ef328d2f2fcbf X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/149 X-Sequence-Number: 28388 ------=_Part_7682_20542695.1200684915769 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline On Jan 18, 2008 2:14 PM, Greg Smith wrote: > On Fri, 18 Jan 2008, Sean Davis wrote: > > > FYI, here are the specs on the server. > > http://www.thinkmate.com/System/8U_Dual_Xeon_i2SS40-8U_Storage_Server > > Now we're getting somewhere. I'll dump this on-list as it's a good > example of how to fight this class of performance problems. > > The usual troubleshooting procedure is to figure out how the motherboard > is mapping all the I/O internally and then try to move things out of the > same path. That tells us that you have an Intel S5000PSL motherboard, and > the tech specs are at > > http://support.intel.com/support/motherboards/server/s5000psl/sb/CS-022619.htm > > What you want to stare at is the block diagram that's Figure 10, page 27 > (usually this isn't in the motherboard documentation, and instead you have > to drill down into the chipset documentation to find it). Slots 5 and 6 > that have PCI Express x16 connectors (but run at x8 speed) both go > straight into the memory hub. Slots 3 and 4, which are x8 but run at x4 > speed, go through the I/O controller first. Those should be slower, so if > you put a card into there it will have a degraded top-end performance > compared to slots 5/6. > > Line that up with the layout in Figure 2, page 17, and you should be able > to get an idea what the possibilities are for moving the cards around and > what the trade-offs involved are. Ideally you'd want both 3Ware cards to > be in slots 5+6, but if that's your current configuration you could try > moving the less important of the two (maybe the one with less drives) to > either slot 3/4 and see if the contention you're seeing drops. > Greg, this is GREAT information and I'm glad you stepped through the process. It is really interesting to see to what extent these slots that have similar names (or the same names) should be expected to behave so differently. We'll try some of the things you suggest (although it will probably take a while to do) and if we come to any conclusions will let everyone know our conclusions. Sean ------=_Part_7682_20542695.1200684915769 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline

On Jan 18, 2008 2:14 PM, Greg Smith <gsmith@gregsmith.com> wrote:
On Fri, 18 Jan 2008, Sean Davis wrote:

> FYI, here are the specs on the server.
> http://www.thinkmate.com/System/8U_Dual_Xeon_i2SS40-8U_Storage_Server

Now we're getting somewhere.  I'll dump this on-list as it's a good
example of how to fight this class of performance problems.

The usual troubleshooting procedure is to figure out how the motherboard
is mapping all the I/O internally and then try to move things out of the
same path.  That tells us that you have an Intel S5000PSL motherboard, and
the tech specs are at
http://support.intel.com/support/motherboards/server/s5000psl/sb/CS-022619.htm

What you want to stare at is the block diagram that's Figure 10, page 27
(usually this isn't in the motherboard documentation, and instead you have
to drill down into the chipset documentation to find it).  Slots 5 and 6
that have PCI Express x16 connectors (but run at x8 speed) both go
straight into the memory hub.  Slots 3 and 4, which are x8 but run at x4
speed, go through the I/O controller first.  Those should be slower, so if
you put a card into there it will have a degraded top-end performance
compared to slots 5/6.

Line that up with the layout in Figure 2, page 17, and you should be able
to get an idea what the possibilities are for moving the cards around and
what the trade-offs involved are.  Ideally you'd want both 3Ware cards to
be in slots 5+6, but if that's your current configuration you could try
moving the less important of the two (maybe the one with less drives) to
either slot 3/4 and see if the contention you're seeing drops.

Greg, this is GREAT information and I'm glad you stepped through the process.  It is really interesting to see to what extent these slots that have similar names (or the same names) should be expected to behave so differently.  We'll try some of the things you suggest (although it will probably take a while to do) and if we come to any conclusions will let everyone know our conclusions. 

Sean


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