Can anyone provide a tutorial or advice on how to configure a software RAID 5 from the command-line (since I did not install Gnome)? I have 8 x 1.5tb Drives. -Jason
At Thu, 25 Mar 2010 12:24:57 -0700 (PDT) CentOS mailing list <centos at centos.org> wrote:> > > Can anyone provide a tutorial or advice on how to configure a software RAID 5 from the command-line (since I did not install Gnome)? > > I have 8 x 1.5tb Drives.mdadm --create /dev/md0 --level=5 --raid-devices=7 /dev/sd[abcdefg]1 The above will create a level 5 RAID named /dev/md0 of /dev/sda1 /dev/sdb1 /dev/sda1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1, with hot-spare /dev/sdg1 Note: RAID5 is not really recomended for such large disks. You run the risk of a complete data loss if one disk fails and the another disk fails during the rebuild.> > -Jason > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > >-- Robert Heller -- 978-544-6933 Deepwoods Software -- Download the Model Railroad System http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows heller at deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/
On 3/25/2010 2:24 PM, Slack-Moehrle wrote:> > Can anyone provide a tutorial or advice on how to configure a software RAID 5 from the command-line (since I did not install Gnome)? > > I have 8 x 1.5tb Drives.Make matching partitions on each disk with fdisk, setting the type to FD (raid autodetect), then 'mdadm create ...' to specify the options and start it. See the create section in 'man mdadm'. You'll need at least --raid-level= --raid-devices= --auto=yes. Then you'll probably want to add an entry in /etc/fstab to mount the new md device somewhere. -- Les Mikesell lesmikesell at gmail.com
>As the disks get bigger, rebuild time also increases and the >performance of the disks don't increase linearly with their storage. >This means that when you are rebuilding a disk, the chances of one of >your other disks failing becomes significantly large. Most suggest >RAID6 these days as a minimum, mirroring and striping appears to be >the most popular.I looked up RAID6 and see the addition or a parity bit. http://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_6 RAID 10 is also something I looked at. Striped, then Mirrored So: 8 x 1.5tb = 12tb RAID 5 = 12tb - 1.5tb for parity data = 10.5tb space available RAID 10 = 4 x 1.5 = 6tb - 1.5tb for parity data = 4.5tb per stripe then mirror it. but with RAID 10, data is safe after many types of failures.