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Re: Root on RAID

On Fri, 3 Aug 2001 06:19, Brian May wrote:
>     Alvin> hi ya george
>     Alvin> for raid1....  typically /dev/hda is copied to /dev/hdb
>     Alvin> 	- dont know why you'd wanna mirror a partition...  (
>     Alvin> system will still be dead since the rest of the required (
>     Alvin> partition is not available
> Easy, you create a separate software-RAID1 partition for every
> partition on you harddisk, so in affect you mirror one harddisk on to
> the other harddisk.
> It might be possible (?) to mirror /dev/hda to /dev/hdb, but then you
> need to subdivide that space up into partitions.

Sure, it's quite possible to mirror /dev/hda to /dev/hdb, but then the 
auto-detect RAID stuff (which relies on having partition type 0xfd) won't 
work.  But then it won't work with RAID in a module on an initrd either - and 
with the modern setup this is what you should be doing.

> lvm could be used to do this (AFAIK), but all my attempts to use lvm
> up to now have failed.

Yes.  Ideally you mirror the raw devices (if the sizes match) and then run 
LVM on that.  For different size disks you have to mirror a whole disk to a 
partition on the larger disk, but such mirroring won't give best performance 

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