[Mageia-discuss] Partitioning tools

andre999 andr55 at laposte.net
Fri Jun 10 06:02:59 CEST 2011

David W. Hodgins a écrit :
> On Thu, 09 Jun 2011 09:33:23 -0400, Doug Lytle <support at drdos.info> wrote:
>> I've purchased a Hitachi 3TB drive that uses 4k sectors.
> The drive is using 4k physical sectors. Is it using 512 byte logical
> sectors or 4k logical sectors?
> If it's using 4k logical sectors, you don't have to worry about
> alignment.
> If it's using 512 byte logical sectors, then you have two things to do.
> Ensure partitions are aligned on 4k boundaries.
> Use a gpt partition table, instead of a msdos style partition table,
> as the msdos partition table cannot address anything beyond 2TB, due
> to the use of 32 bit sector numbers.

A gpt partition table is also more secure, with a backup table at the end of the disk.
Gpt typically has 128 partitions, all primary.  Gpt doesn't have secondary partitions, thus 
avoiding the associated daisy-chaining.  Additionally, a gpt table takes less space than the 
equivalent mbr format with secondary partitions.
> I'd use gparted to partition the drive. In gparted, select Device,
> Create partition table, Advanced, and use the drop down button to
> select a partition table type of gpt. This creates a msdos style
> mbr with a fake 2TB partition, so that older partitioning tools
> like fdisk won't see any free space, and uses the guid partition
> table to store information about the real partitions. See
> http://en.wikipedia.org/wiki/GUID_Partition_Table for details.
> I think gparted will default to aligning the partitions on 1MB
> boundaries, which is a multiple of 4k.

That is my understanding as well.

> After you've partitioned the drive with gparted, you may be able to
> use diskdrake to specify the mount points, and create the fstab
> entries, but I'm not sure if it will work with a gpt partition table,
> as I've never tried it.

It would be much _safer to simply edit /etc/fstab to change the mount points.  (Creating any 
corresponding folders as needed.)
You _could_ use diskdrake to specify the mount points, but it is very risky to do any other changes.
When I tried some other changes with Mandriva 2010.0, it corrupted the partition table -- every 
time.  (I didn't realise the cause until I specifically tested for corruption.)
I had to boot using systemrescuecd, and use gdisk on the cd, to repair the partition table.
(If you procede carefully, gdisk, now in Mageia, is a useful tool for gpt disks, much like fdisk 
for mbr disks.)

> Regards, Dave Hodgins


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