1. How does one recover from software RAID (mirroring). Meaning .. if
the primary drive that the PC boots from fails, how do you tell it to
automatically boot from the secondary drive. Assume that I am using
adaptec scsi and the boot drive is ID 0 and secondary mirror drive is ID 1.

2. Any one know of any good external rackable 1U SCSI->RAID enclosures
that has good value and is reliable and is not too pricey? With
controllers included please..

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On Wed, 12 Jan 2005 03:41:45 -0500, Deke wrote:

> 1. How does one recover from software RAID (mirroring). Meaning .. if
> the primary drive that the PC boots from fails, how do you tell it to
> automatically boot from the secondary drive. Assume that I am using
> adaptec scsi and the boot drive is ID 0 and secondary mirror drive is ID
> 1.

This is controlled using the bootloader, either GRUB or LILO.

Look at the "/etc/grub.conf" file:

title Fedora Core (2.6.9-1.724_FC3)
root (hd0,5)
kernel /vmlinuz-2.6.9-1.724_FC3 ro root=LABEL=/
initrd /initrd-2.6.9-1.724_FC3.img

The "root=FOO" tells the kernel where to find the root filesystem.

HTH.

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Deke wrote:
> 1. How does one recover from software RAID (mirroring). Meaning .. if
> the primary drive that the PC boots from fails, how do you tell it to
> automatically boot from the secondary drive. Assume that I am using
> adaptec scsi and the boot drive is ID 0 and secondary mirror drive is ID 1
.
>
> 2. Any one know of any good external rackable 1U SCSI->RAID enclosures
> that has good value and is reliable and is not too pricey? With
> controllers included please..
IF you really had RAID 0 - mirroring going, just unplug the bad drive.
If it does not boot, you didn't have Raid 0 working. For Hardware
Raid you need to set a new drive in & config.
There is also a difference if it was hardware Raid or software raid.
I had RH using software raid .... lots of other problems it created
not relating to raid.

Kahn

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frank schrieb:
> Deke wrote:
> 
>
> IF you really had RAID 0 - mirroring going, just unplug the bad drive.
> If it does not boot, you didn't have Raid 0 working. For Hardware
> Raid you need to set a new drive in & config.

Just to be correct: the RAID level for mirroring is RAID 1. RAID 0 is
striping which means that if one drive of the stripe set fails you loose
all your data on that stripe set.

> There is also a difference if it was hardware Raid or software raid.

Thats correct, but if Deke would have a hardware RAID he would have
gotten an error message but his system would be still useable/bootable.
So I assume he's using a software RAID. Ideally (if he has configured
his system using disk labels) he just has to unplug the broken disk to
get his system back to life-without the RAID on the boot device. In the
second step he should edit his grub.conf to change the boot device from
/dev/sda to /dev/sdb power down the system, put in the replacement for
the defective disk, reboot, partition and configure the new disk to act
as mirror for /dev/sdb. The driver should the recognize the
inconsistency of the RAID and start a rebuild of the mirror.

HTH

Andre
--
Andre von Raison

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