[CentOS] Large disk support

Kevan Benson kbenson at a-1networks.com
Tue Nov 28 23:04:35 UTC 2006

On Tuesday 28 November 2006 13:07, chrism at imntv.com wrote:
> Kevan Benson wrote:
> > I have a 3.5 TB RAID 5 Array through a 3ware 9590SE 8 port card, and am
> > running into what seems like quite a lot of problems trying to get the
> > system installed correctly.  The system is a running dual Opterons with 2
> > GB of RAM, and I'm attempting to install through the x86_64 ServerCD.
> >
> > First, grub refuses to install on the disk, as it's too large.  I can get
> > around this though by booting Fedora Core 6 in rescue mode and running
> > grub, as it can deal with the disk size correctly.  This might only be
> > working when I attempt installs that don't utilize as much of the array
> > as possible though (100 MB /boot, 2GB swap, 10Gb /, the rest left
> > unallocated).
> >
> > Secondly, there seems to be a problem using msdos disk labels with large
> > partitions, and I can't seem to find any solutions to this in the manuals
> > or on the net.  GPT labels are offered as a solution to this but only for
> > Itanium systems.
> >
> > Am I missing some obvious solution to this?  Are there some best
> > practices for dealing with large disks anyone can share that may save me
> > problems now or later?  I'm open to suggestions, as all I've encountered
> > so far are problems.
> On two different systems with hardware similar to yours, I ended up
> using 2 different solutions.  :)  On one, I simply replaced 2 of the
> 750gig 'cudas in an 8 disk array with 160gig drives and then created a
> RAID1 on those 2 drives for the OS.  After the OS was installed, I then
> used parted to create the gpt label on the large array and created the
> filesystem on it.
> On another system, I really needed the ports on the 3ware for the array
> so I installed a pair of 160gig drives using a cheapo dual port SATA
> card and used software RAID 1 on those two drives for the OS install.
> After the system was installed, I then used parted to create the GPT
> label on the large array and created the filesystem on it.
> If you go back through the list archives a bit, you'll see a bunch of
> very useful information from a couple of months ago where a number of
> people offered excellent tuning suggestions.  If you get stuck, shoot me
> some email off list and I'll see if I can give you a hand.

Thanks for all the suggestions, and to Joshua for mentioning 3ware's carving, 
which I wasn't aware of before this.

Carving with LVM to append portions into a large LV seems to be the solution 
I'm leaning towards, as it seems to be the easiest to implement "out of the 
box" and I expect it will cause the least issues in the long run as there's 
no room in the chassis for more drives (it also has a tape drive) and 
dedicating one or two 500 GB drives to an install array seems wasteful.

- Kevan Benson
- A-1 Networks

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