[clug] linux Digest, Vol 117, Issue 1

[rodneyp at pcug.org.au]

On Sat, 1 Sep 2012 12:00:03 eyal wrote:
> Message: 2
> Date: Sat, 01 Sep 2012 18:49:42 +1000
> From: Eyal Lebedinsky <eyal at eyal.emu.id.au>
> To: list CLUG <linux at lists.samba.org>
> Subject: [clug] 3TB (4k sector) disk question
> Message-ID: <5041CC26.1030603 at eyal.emu.id.au>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> [This is up to date f16]
> 
> Today I bought a 3TB disk, which originally was in a USB3 case (now out of
> it).
> 
> When introduced linux (as bare SATA) it seems that a sector size of 512B is
> used, and the disk size is limited.
> 
> 'hdparm -I' knows that this is a native 4k disk:
>         Model Number:       ST3000DM001-9YN166
>         Logical  Sector size:                   512 bytes
>         Physical Sector size:                  4096 bytes       
>         Logical Sector-0 offset:                  0 bytes       
>         device size with M = 1024*1024:     2861588 MBytes
>         device size with M = 1000*1000:     3000592 MBytes (3000 GB)
> 
> However parted thinks otherwise (I created one large GPT partition):
> 
> # parted /dev/sdi
> GNU Parted 3.0
> Using /dev/sdi
> Welcome to GNU Parted! Type 'help' to view a list of commands.
> (parted) print
> Model: ATA ST3000DM001-9YN1 (scsi)
> Disk /dev/sdi: 2199GB
> Sector size (logical/physical): 512B/512B
> Partition Table: gpt
> 
> Number  Start   End     Size    File system  Name     Flags
>   1      1049kB  2199GB  2199GB  ext2         primary
> 
> Note the line 'Sector size (logical/physical): 512B/512B'.
> 
> How do I make linux use 4k sector size? Or is there a jumper
> on the disk? Or a special SATA command to configure the disk?
> 
> Also, should GPT not be able to create very large disks even with 512B
> sectors, using the 64bit internal pointers/sizes/etc.? Where is the
> disk size limit coming from?
> 
> TIA
>         Eyal
> 
> -- 
> Eyal Lebedinsky (eyal at eyal.emu.id.au)

I've sucessfully partitoned HDD as small as *4 GB* with GPT using parted or 
gdisk.  The latter has much better defaults, implements more of the GPT 
features and optimises the disk better for 4k physical sectors/blocks. 

No jumpers were required - however I've never had a 3 TB disk.   It's possible 
that the latter have a jumper to nobble them back to 512 B sectors, for 
Windows. 

openSUSE & Ubuntu handle GPT partition tables correctly, from my first hand 
experience, as do their patched GRUB 0.97.  I would expect Fedora to do 
likewise.

I suggest that you let  gdisk 'have its head" in creating a new disk label and  
aligning partitions to 1 MBi boundaries etc..  Several factors to consider for 
a well implemented GPT, particularly if used with a (U)EFI mainboard - see 

 http://www.rodsbooks.com/gdisk/

-- 
Rod