Linux and drives > 2 terabytes; questions.

[Anthony Verevkin]

The biggest problem with ++2 TB drives is that MBR partition table does
not support partition sizes of more than 2TB. I am not sure how big you
can go with your total disk size, but I believe you can still have
multiple partitions of 2TB each (obviously 4 partitions max, but maybe
there is another smaller limit for total disk size as well).

If you want partitions larger than 2TB you need to set up GPT partition
table and parted is your tool here. However GRUB v1 (0.9x) lacks support
for GPT. They say there is a patch. But your best bet would be GRUB v2
(1.9x).

Also, and it is true not just for the 3TB drives, for it started earlier
- they now make disk sectors of 4k size, not 512b. And if you look at
your old partition table loolking at sectors not cylinders (fdisk -u)
you will see that your first partition starts on the 63rd 512-byte
sector. That is somewhere in the middle of a 4k sector. And so all the
4k blocks of that partition would be aligned to the middle of a 4k sector
of the drive, thus almost doubling the amount of reads and writes to
the drive.

What you want to do is to check that the beginning of your
partitions when shown as a 512-byte number (fdisk -u) would be a number
that divides by 8. The new default of 2048-th sector for the first
partition is just fine. Look at your other partitions as well.

Regards,
Anthony

----- Original Message -----
> From: "Walter Dnes" <waltdnes-SLHPyeZ9y/tg9hUCZPvPmw at public.gmane.org>
> To: "Toronto Linux Users Group" <tlug-lxSQFCZeNF4 at public.gmane.org>
> Sent: Wednesday, April 3, 2013 7:08:04 PM
> Subject: [TLUG]: Linux and drives > 2 terabytes; questions.
> 
> I picked up a 2 TB external USB drive for backup use today.  I
> noticed
> a few 3 TB drives were available.  So here are my questions.  I think
> I
> know the answers, but I've done stuff like that before,  So to save
> myself potential embaressment, I want to confirm...
> 
> 1) I know that "legacy-booting" linux only works up to 2.1 TB.  Can I
> make multiple partions?  E.g. boot from a 250 meg partition, and have
> the rest of a large drive mounted as one or more partitions?  This is
> a
> throwback to the old days of having the boot partition entirely
> within
> the first 1024 cylinders.
> 
> 2) For non-boot usage (e.g. external USB drives), I don't think that
> 2.1
> TB should be a problem.  I use ReiserFS, which can handle up to a 16
> TB
> partion.  Is that correct?
> 
> --
> Walter Dnes <waltdnes-SLHPyeZ9y/tg9hUCZPvPmw at public.gmane.org>
> I don't run "desktop environments"; I run useful applications
> --
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