From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Szecsei Subject: Re: Confusion with setting up new RAID6 with mdadm Date: Mon, 15 Nov 2010 08:52:32 +0200 Message-ID: <4CE0D8B0.4050603@geograph.co.za> References: <4CE00206.4000301@geograph.co.za> <20101114195036.GA23982@maude.comedia.it> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20101114195036.GA23982@maude.comedia.it> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 2010-11-14 21:50, Luca Berra wrote: > On Sun, Nov 14, 2010 at 05:36:38PM +0200, Zoltan Szecsei wrote: >> >> *Partition alignment? >> Is this relevant for modern HDs (I'm using 5900rpm Seagate 2TB drive= s) > for modern hdds with 4k sectors it is > new fdisk and/or parted should already know how to align fdisk reports 512b sectors: root@gs0:/home/geograph# fdisk -lu WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util=20 fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 256 heads, 63 sectors/track, 242251 cylinders, total 3907029168 sectors Units =3D sectors of 1 * 512 =3D 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sda1 63 3907024127 1953512032+ fd Linux raid=20 autodetect (All 8 disks are as above) > in any case, since you want to use the whole space for raid, why crea= te > partitions at all, md works nicely without OK > >> *Chunk size: >> After reading MANY different opinions, I'm guessing staying at the=20 >> default chunk size is optimal? Anyone want to add to this argument? > i believe the default in newer mdadm is fine > >> >> *After partitioning the 8 drives, is this the correct sequence? >> mdadm --create /dev/md0 --metadata=3D1.2 --auto=3Dmd --chunk=3D64=20 >> --level=3Draid6=20 > why you state the chunk size here, i tought you wanted to stay with t= he > defauklt because on my mdadm, 64 is the default - and I was just re-enforcing=20 that for the reader. root@gs0:/home/geograph# mdadm -V mdadm - v2.6.7.1 - 15th October 2008 root@gs0:/home/geograph# >> *After this, do I mkfs ext4 first, or LVM first? > if you want to use lvm it would be lvm first, but... do you want to? > there is no point if the aim is allocating the whole space to a singl= e > filesystem. Because I might want to join this array to another one at a later stage= =20 - I would then have 2 boxes each with 8 drives, and each with a SiI3132= =20 card on the same motherboard. I might use the second box to mirror the first, or to extend it - not=20 sure of my needs yet. > >> *What stride and stripe values should I use? > new toolstack should already find the correct stripe/stride for you How would I check ? root@gs0:/home/geograph# mkfs.ext4 -V mke2fs 1.41.11 (14-Mar-2010) Using EXT2FS Library version 1.41.11 root@gs0:/home/geograph# > > one more note: > for such a big array i would suggest to create a bitmap, so in case o= f > an unclean shutdown you do not have to wait for 27 hours for it to > rebuild. an internal bitmap will do. > Nice tip - I'll look into it - Thanks, 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: 424/3256 - Release Date: 11/14/10 -- 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