From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roy Sigurd Karlsbakk Subject: Re: Disk speed comparison Date: Sun, 23 Dec 2012 06:29:39 +0100 (CET) Message-ID: <2944870.0.1356240579079.JavaMail.root@zimbra> References: <50D68FC0.70807@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <50D68FC0.70807@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: stan@hardwarefreak.com Cc: linux-raid List-Id: linux-raid.ids > > I have an array with 6 2TB drives plus a spare. While this works > > well, I can from the munin graphs at > > http://munin.karlsbakk.net/munin/karlsbakk.net/smilla.karlsbakk.net= /index.html > > that the WD2001FASS drives (sd[bcfg]) perform some 30% better than > > the Hitachi HDS723020BLA642 drives (sd[eh]). The drives are on a > > mixed set of controllers, so this shouldn't be relevant. Since they > > all are specified to spin on 7200RPM, I find it wierd that the > > performance difference shown by the Munin graph is so big. >=20 > You've provided zero information about the controllers or the > configuration of the drives. If the SATA ASIC to which the Black > drives > are connected is AHCI and the other is not, then NCQ may account for > the > difference in performance. Or, both may currently be AHCI, but > possibly > the Hitachi drives perform better with NCQ disabled. This would not b= e > rare. If you laid partitions on the Hitachi drives and misaligned > them, > this could easily cause a 30% deficit. Etc, etc. >=20 > I doubt there is a 30% overall performance difference between these > two > drive models. The Black models are "enthusiast" class drives, and do > have some additional performance features, but not that I'd think > would > yield a 30% advantage. >=20 > You need to dig deeper into the details. no partitions on this setup, just plain drives. what munin tells me is = those WD drives are rather faster than the hitachis. As noted, all driv= es are on a mixed controller setup, the hitachis and wd drives share co= ntrollers for some. the only known common factor for the slow and fast = drives are their label. --=20 Vennlige hilsener / Best regards roy -- Roy Sigurd Karlsbakk (+47) 98013356 roy@karlsbakk.net http://blogg.karlsbakk.net/ GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt -- I all pedagogikk er det essensielt at pensum presenteres intelligibelt.= Det er et element=C3=A6rt imperativ for alle pedagoger =C3=A5 unng=C3=A5= eksessiv anvendelse av idiomer med xenotyp etymologi. I de fleste tilf= eller eksisterer adekvate og relevante synonymer p=C3=A5 norsk. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html