[CentOS-docs] New page on installing to software RAID

JohnS jses27 at gmail.com
Mon Apr 27 22:54:44 UTC 2009

On Mon, 2009-04-27 at 21:48 +0200, Marcus Moeller wrote:
> Dear Phil,
> > http://wiki.centos.org/HowTos/SoftwareRAIDonCentOS5
> >
> > Comments and corrections please.
> Sorry Phil. I personally cannot accept this HowTo at current state.
> There is also some cute documentation available in the Deployment
> Guide.
> You wrote:
> 'Some controllers claim to be RAID but require Windows drivers to
> function, similar to winmodems.'
> This is not true. Some controllers make use of OS functionality. This
> is not dependent to Windows.
> You wrote:
> 'Booting will only work from non-RAID or RAID1 partitions. RAID0 or
> RAID5 will not work.'
> This is only true if you wish to have the boot partition (/boot/)
> reside on a RAID parition. In this case it must be on a RAID1
> partition.
> Also, in your scenario it does not make much sense to split /boot and
> may cause confusion, as it's not necessary on a RAID1.
> You wrote:
> 'Disable any hardware-based RAID in the motherboard or RAID controller BIOS '
> Why that? I have some systems where I combine hardware- and softraids.
> This may be the case on fakeraid controllers.
> ...skipping...someone else could take care...
> You wrote:
> After installing a new kernel, repeat Section Three. It should be
> possible to apply a similar approach to a /boot on RAID1, or to a / on
> RAID1 without a /boot.
> Why should someone want to use dd to mirror a / partition on an active RAID1 ?

You should not use dd on any active disk raid or not. You might not the
first time end up with errors but you will eventually. One option is to
rsync it then fsck it on a live disk if your brave. The best option is
to mark the disk inactive load the hot spare then let it rebuild. Or
shut down the machine then use a live cd then dd /.


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