Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 412366326F9 for ; Wed, 23 Jun 2010 09:25:19 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 71967-08 for ; Wed, 23 Jun 2010 12:25:10 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mail.postgresql.org (Postfix) with ESMTP id 2CFFF631ADA for ; Wed, 23 Jun 2010 09:25:11 -0300 (ADT) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1ORP0t-0001h9-0t for pgsql-performance@postgresql.org; Wed, 23 Jun 2010 14:25:07 +0200 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Jun 2010 14:25:06 +0200 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Jun 2010 14:25:06 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: pgsql-performance@postgresql.org From: Ivan Voras Subject: Re: raid10 write performance Date: Wed, 23 Jun 2010 14:25:05 +0200 Lines: 14 Message-ID: References: <4C20CB5F.2030000@2ndquadrant.com> <82fx0et0ve.fsf@mid.bfk.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.1.9) Gecko/20100518 Thunderbird/3.0.4 In-Reply-To: <82fx0et0ve.fsf@mid.bfk.de> X-Enigmail-Version: 1.0.1 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201006/393 X-Sequence-Number: 39249 On 06/23/10 14:00, Florian Weimer wrote: > * Ivan Voras: > >> On the other hand, RAID10 is simple enough that soft-RAID >> implementations should be more than adequate - any ideas why a dedicated >> card has it "slow"? > > Barrier support on RAID10 seems to require some smallish amount of > non-volatile storage which supports a high number of write operations > per second, so a software-only solution might not be available. If I understand you correctly, this can be said in general for all spinning-disk usage and is not specific to RAID10. (And in the case of high, constant TPS, no amount of NVRAM will help you).