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Re: [SOLVED] Re: Partitioning And Formatting A Large Disk (2086.09GB)

On Thu, Feb 01, 2007 at 01:06:54PM -0500, Michael S. Peek wrote:
> So the consensus seems to be that LVM is the way to go.
> So what's the cutoff between building arrays of varying size versus 
> grouping them under LVM?
> I.e. Right now I've got two large arrays.  Should I maybe break that 
> down unto just a bunch of disks and then use LVM to group them together 
> (not use hardware RAID at all), or should I break the disks into each 
> bundles of three and make as many small raid5 arrays as I can and then 
> group them under LVM?
> What's the general consensus on actually using LVM with hardware RAIDs?

Separate the two concepts:
	raid protects you from drive failure

	LVM allows you to move partitions from one block device (drive,
	raid array, whatever) to another and to resize those partitions.

So do both.

If you're using hardware raid and one disk starts failing, I would think
that you would want one port free on your hardware controller where you
can add a new disk (or leave a hot spare) to allow swapping out a
failing (but not totally failed) drive without degrading the array by
pulling the failing drive first.

Since I've never had a hardware raid card, I could be wrong on this.

If I recall correctly, the drive-space efficiency goes up the more
drives you have in a raid5 array.  If you broke it up into 3-drive
arrays, you'd only have 66% efficiency vs whatever you have now.

I'm assuming that your two large arrays aren't one huge array because of
using two hardware raid controllers.

Personally, I'd use both arrays as PVs for LVM.  Then the LVs can be
made stripe for better performance (since raid protects you from drive

FYI, remember that /boot can't be on lvm.  I have mine on a raid1.

I have no idea how to set this up after install if you're wanting / on
LVM.  I did mine during Etch install.

Since you're going to all this trouble, choose a good FS like XFS or

Enjoy your terror-bites of storage :-)


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