Re: Concern for my data on large partition

[Bryn M. Reeves]

On Wed, 2009-08-19 at 04:43 +1200, Space Ship Traveller wrote:
> Dear Bill
> 
> 
> It is great that you are experimenting with file systems and large
> partitions. This is an area where things start to get quite complex
> and there is no single best practise solution. Linux is a great tool
> but is by no means the only option. Some higher end NAS products and
> SAN products may provide a better and easier to administer solution.
> 3ware make good cards, but if performance is not a high priority,
> Linux software raid is also fairly capable.
> 
> 
> I noticed a few things:
> - msdos partition format is actually limited to 2TB partitions. So you

Not quite - the MSDOS MBR cannot represent offsets larger than 2TB, so
it's not just that partitions may not exceed this size. No offset
(beginning or ending) of a partition may exceed 2TB on an MBR-labeled
device. I.e. it's not possible to safely take a device >2TB in size and
divide it into partitions that are 2TB or less in size.

>  might want to try using GPT (use mklabel gpt).
> - fdisk doesn't support large partitions. you should be exclusively
> using parted at this point.

GPT is the only sensible choice if you're determined to partition a
device of this size. Be aware that it does have some caveats - in
particular, most non-ia64 systems cannot boot from GPT volumes without
resorting to brittle hacks.

> http://www.google.com/search?hl=en&client=safari&rls=en-us&q=large
> +partitions+linux+LVM&aq=f&oq=&aqi=

Using a volume manager is certainly a reasonable approach here, just
make sure you use LVM2 and either create PVs on whole-disk devices or
GPT partitions.

Regards,
Bryn.