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Re: Software RAID on a single partition?



hi ya jon

On Sun, 8 Feb 2004, Jonathan Melhuish wrote:

> Say I've got the following files:
> 
> *  Some small files that I want to keep safe, eg. document backups, 
> databases, etc.
> *  Some big files that I don't care much about losing but need to read 
> quickly, eg. video
> 
> Can I use software RAID-1 (mirroring) on a partition containing the 
> first type of files and RAID-0 (striping) on the other partition?
> 
> The Software-RAID-HOWTO kind-of implies that you can do this by 
> specifying a partition number in the |/etc/raidtab file, but the 
> description refers to "devices" throughout, not "partitions".|

if you use /dev/hda  and /dev/hdc...
you can get what you;re looking for

say ...
	/dev/hda1 + /dev/hdc1	--> mirroring

	/dev/hda2 + /dev/hdc2   --> stripping 

for stripping (reading off 2 disks at the same time .. reading 2x faster)
you'd want to mirror the data first, than strip it

	/dev/hda2 + /dev/hdc2 --> mirror1 ( /dev/md0 )
	/dev/hde2 + /dev/hdg2 --> mirror2 ( /dev/md1)
	
	/dev/md0 + /dev/md1 ---> stripping

count the disk spindles... you can only go as fast as the disk is
spinning .. read faster ... write would be equally slower

c ya
alvin



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