[CentOS] Anaconda doesn't support raid10

Mon May 7 20:51:04 UTC 2007
Ross S. W. Walker <rwalker at medallion.com>

> -----Original Message-----
> From: centos-bounces at centos.org 
> [mailto:centos-bounces at centos.org] On Behalf Of Ruslan Sivak
> Sent: Monday, May 07, 2007 4:00 PM
> To: CentOS mailing list
> Subject: Re: [CentOS] Anaconda doesn't support raid10
> 
> Ross S. W. Walker wrote:
> >> -----Original Message-----
> >> From: centos-bounces at centos.org 
> >> [mailto:centos-bounces at centos.org] On Behalf Of Ruslan Sivak
> >> Sent: Monday, May 07, 2007 12:53 PM
> >> To: CentOS mailing list
> >> Subject: [CentOS] Anaconda doesn't support raid10
> >>
> >> So after troubleshooting this for about a week, I was 
> finally able to 
> >> create a raid 10 device by installing the system, copying the 
> >> md modules 
> >> onto a floppy, and loading the raid10 module during the install. 
> >>
> >> Now the problem is that I can't get it to show up in anaconda.  It 
> >> detects the other arrays (raid0 and raid1) fine, but the 
> raid10 array 
> >> won't show up.  Looking through the logs (Alt-F3), I see the 
> >> following 
> >> warning:
> >>
> >> WARNING: raid level RAID10 not supported, skipping md10. 
> >>
> >> I'm starting to hate the installer more and more.  Why won't 
> >> it let me 
> >> install on this device, even though it's working perfectly 
> from the 
> >> shell?  Why am I the only one having this problem?  Is nobody 
> >> out there 
> >> using md based raid10? 
> >>     
> >
> > Most people install the OS on a 2 disk raid1, then create a separate
> > raid10 for data storage.
> >
> > Anaconda was never designed to create RAID5/RAID10 during install.
> >
> > -Ross
> >
> >   
> 
> Whether or not it was designed to create a Raid5/raid10, it 
> allows the 
> creating of raid5 and raid6 during install.  It doesn't, 
> however, allow 
> the use of raid10 even if it's created in the shell outside 
> of anaconda 
> (or if you have an old installation on a raid10). 
> 
> I've just installed the system as follows
> 
> Raid1 for /boot with 2 spares (200mb)
> raid0 for swap  (1GB)
> raid6 for / (10GB)
> 
> after installing, I was able to create a raid10 device and 
> successfully 
> mount and automount by using /etc/fstab
> 
> Now to test what happens when a drive fails.  I pulled out the first 
> drive - Box refuses to boot.  Going into rescue mode, I was able to 
> mount /boot, was not able to mount the swap drive (as to be 
> expected, as 
> it's a raid0), was also not able to mount the / for some 
> reason, which 
> is a little surprising. 
> 
> I was able to mount the raid10 parition just fine. 
> 
> Maybe I messed up somewhere along the line.  I'll try again, but it's 
> disheartening to see that a raid6 array would die after one drive 
> failure, even if it was somehow my fault. 
> 
> Also assuming that the raid5 array could be recovered, what 
> would I do 
> with the swap partition?  Would I just recreate it from the 
> space in the 
> leftover drives and would that be all that I need to boot? 

Ok, my bad raid5/6 can be created during install even if OS
can't boot from it.

I guess raid10 is the red headed stepchild of anaconda...

I suggest this:

/dev/md0 raid1, 128MB partition, all 4 drives, for /boot
/dev/md1 raid1, rest of drive space, first 2 drives, for lvm
/dev/md2 raid1, rest of drive space, second 2 drives, for lvm

lvm volgroup CentOS, comprised of /dev/md1 and /dev/md2
	logical vol1, root, interleave 2, mount /, 16GB
	logical vol2, swap, interleave 2, swapfs, 4GB

This will provide the same performance and fail-over as a raid10.

If you remove the first disk and boot make sure BIOS is set to boot
off of disk2!

-Ross

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