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Re: Root on RAID



hi ya brian

yes... i suppose it's just as easy ( better ) to clone the 
partitions... ( i must a been out to lunch when i replied earlier )

yes.. sometimes one mirrors diska to diskb of a different size...

yes... having raid is NOT a backup of important data...so if one
detects some flakyness.... back up that data to a clean disk/system
	- but than again... if its being mirrored...stop the mirroring
	to prevent the possibly bad data from corrupting the good data
	on the other disk or vice versa...

	- i always incrementally backup the raid to another box...
	usually compressed to save space...

i havent played with lvm... mostly scsi3 and plain ole ide...

and yup... i disconnect the disks to see if its "raiding properly"...

have fun raiding...
alvin
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On 3 Aug 2001, Brian May wrote:

> >>>>> "Alvin" == Alvin Oga <aoga@Maggie.Linux-Consulting.com> writes:
> 
>     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.
> 
> lvm could be used to do this (AFAIK), but all my attempts to use lvm
> up to now have failed.
> 
> Even then, I imagine it would be harder/impossible to do some things
> which are possible with a separate RAID partition, eg:
> 
> recently my 20 Gig harddisk failed (or at least showed serious looking
> "unrecoverable" DMA transfer errors), and I didn't trust the other one
> either. I only had 2 * 8 gigs harddisk spare.
> 
> It is an easy matter to create partitions the same size (or bigger) as
> the important partitions on the remaining drive, and mirror them. If I
> mirrored the entire drive, this would not be possible, I would need
> total space at least 20Gigs big.
> 
> Of course, one of my partitions was 10Gig, so this wasn't going to
> work here, so I tried to install a large lvm partition on both hard
> disks. However, my attempts failed, as I couldn't do the 2nd step
> (create a virtual drive from the physical drive, it kept saying no
> physical drives found).
> 
> As for now, I have replaced the dead harddisk, and everything is
> working fine (for the moment).



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