From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Szecsei Subject: Re: mdadm raid6->LVM->ext4 setup Date: Wed, 17 Nov 2010 09:49:27 +0200 Message-ID: <4CE38907.8040709@geograph.co.za> References: <4CE2C8AC.7010103@geograph.co.za> <20101116221722.GC8943@maude.comedia.it> <4CE31641.50909@ziu.info> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4CE31641.50909@ziu.info> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 2010-11-17 01:39, Michal Soltys wrote: > On 10-11-16 23:17, Luca Berra wrote: >> On Tue, Nov 16, 2010 at 08:08:44PM +0200, Zoltan Szecsei wrote: >>> >>> *** Commands used: >>> mdadm --create /dev/md0 --metadata=3D1.2 --auto=3Dmd --assume-clean >>> --bitmap=3Dinternal --bitmap-chunk=3D131072 --chunk=3D512 --level=3D= 6 >>> --raid-devices=3D8 /dev/sd[abcdefgh] >>> mdadm --detail --scan >> /etc/mdadm.conf >>> mdadm --assemble /dev/md0 >> as i said this is not useful Accepted, but I also understood "not harmfull". I tried it out of=20 curiosity, it took a nano-second to complete, so didn't try to "undo it= ". >>> pvcreate --metadatasize 512 /dev/md0 >> you should use --dataalignment, not --metadatasize, also you should I checked out man pvcreate & lvm.conf had all the stuff below in it, so= =20 I assumed it would sort itself out. md_component_detection =3D 1 md_chunk_alignment =3D 1 data_alignment_detection =3D 1 data_alignment_offset_detection =3D 1 > > Also with reference to metadatasize - keep in mind the value is=20 > rounded up to the /next/ 64k boundary (or it was a while ago, perhaps= =20 > it's changed now). So in your case, 512 would really result with 576. > > With reference to --dataalignment - there's also --dataalignoffset=20 > option (although not really important in your setup). > > You might consider adjusting=20 > /sys/block//md/stripe_cache_size to higher values when=20 > you have everything set. It tends to give quite a performance boost. I had trouble getting my head around all the calculations, mainly=20 because I do not know if my sector size of 512 is falsely reported or=20 not (so I just accepted it as 512). I am loading the array as we speak, with 200MB to 400MB tiff files. In=20 the past 11 hours approx 995GB was loaded, so that calculates to a writ= e=20 speed of 25MB/s I have no problem stopping & deleting this if you feel that this=20 represents problems in my setup, but then please can someone do the=20 alignment calculations & command syntax for me. Regards to all, Zoltan --=20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Zoltan Szecsei PrGISc [PGP0031] Geograph (Pty) Ltd. P.O. Box 7, Muizenberg 7950, South Africa. 65 Main Road, Muizenberg 7945 Western Cape, South Africa. 34=B0 6'16.35"S 18=B028'5.62"E Tel: +27-21-7884897 Mobile: +27-83-6004028 =46ax: +27-86-6115323 www.geograph.co.za =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1153 / Virus Database: 424/3261 - Release Date: 11/16/10 -- 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