From mboxrd@z Thu Jan 1 00:00:00 1970 From: CoolCold Subject: Re: Optimize RAID0 for max IOPS? Date: Mon, 24 Jan 2011 17:40:08 +0300 Message-ID: References: <20110118210112.D13A236C@gemini.denx.de> <4D361F26.3060507@stud.tu-ilmenau.de> <20110119192104.1FA92D30267@gemini.denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110119192104.1FA92D30267@gemini.denx.de> Sender: linux-raid-owner@vger.kernel.org To: Wolfgang Denk Cc: stefan.huebner@stud.tu-ilmenau.de, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, Jan 19, 2011 at 10:21 PM, Wolfgang Denk wrote: > Dear =3D?ISO-8859-15?Q?Stefan_/*St0fF*/_H=3DFCbner?=3D, > > In message <4D361F26.3060507@stud.tu-ilmenau.de> you wrote: >> >> [in German:] Sch=E4tzelein, Dein Problem sind die Platten, nicht der >> Controller. >> >> [in English:] Dude, the disks are your bottleneck. > ... > > Maybe we can stop speculations about what might be the cause of the > problems in some setup I do NOT intend to use, and rather discuss the > questions I asked. > >> > I will have 4 x 1 TB disks for this setup. >> > >> > The plan is to build a RAID0 from the 4 devices, create a physical >> > volume and a volume group on the resulting /dev/md?, then create 2= or >> > 3 logical volumes that will be used as XFS file systems. > > Clarrification: I'll run /dev/md* on the raw disks, without any > partitions on them. > >> > My goal is to optimize for maximum number of I/O operations per >> > second. ... >> > >> > Is this a reasonable approach for such a task? >> > >> > Should I do anything different to acchive maximum performance? >> > >> > What are the tunables in this setup? =A0[It seems the usual recipi= es are >> > more oriented in maximizing the data troughput for large, mostly >> > sequential accesses - I figure that things like increasing read-ah= ead >> > etc. will not help me much here?] > > So can anybody help answering these questions: > > - are there any special options when creating the RAID0 to make it > =A0perform faster for such a use case? > - are there other tunables, any special MD / LVM / file system / > =A0read ahead / buffer cache / ... parameters to look for? XFS is known for it's slow speed on metadata operations like updating file attributes/removing files..but things gonna change after 2.6.35 where delaylog is used. Citating Dave Chinner : < dchinner> Indeed, the biggest concurrency limitation has traditionally been the transaction commit/journalling code, but that's a lot more scalable now with delayed logging.... So, you may need to benchmark fs part. > > Thanks. > > Wolfgang Denk > > -- > DENX Software Engineering GmbH, =A0 =A0 MD: Wolfgang Denk & Detlev Zu= ndel > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de > Boykottiert Microsoft - Kauft Eure Fenster bei OBI! > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > --=20 Best regards, [COOLCOLD-RIPN] -- 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