[clug] 3TB (4k sector) disk question
rodneyp at pcug.org.au
rodneyp at pcug.org.au
Tue Sep 4 01:51:52 MDT 2012
I was away yesterday (and not checking my email from the top of Mt Twynam
during a total white-out :-)
I've never dealt with a drive > 2TB and might not be able to enlighten you
AFAIK the -z switch in gdisk is for, most importantly, erasing sectors 1 to 34
prior to replacing GPT disk-label with an MBR/DOS disk-label. You need the -n
switch to create a new disk GPT label. I suggest you try that first.
By way of comparision, my 2TB WD20 EARX reports to hdparm -I
CHS current addressable sectors: 16514064
LBA user addressable sectors: 268435455
LBA48 user addressable sectors: 3907029168
Logical Sector size: 512 bytes
Physical Sector size: 4096 bytes
Logical Sector-0 offset: 0 bytes
device size with M = 1024*1024: 1907729 MBytes
device size with M = 1000*1000: 2000398 MBytes (2000 GB)
and hdparm -V
Results are fairly analagous, but HDD from different manufacturers
gdisk 0.8.5 reports
Logical sector size: 512 bytes
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 3907029134
Partitions will be aligned on 2048-sector boundaries
Number Start (sector) End (sector) Size Code Name
1 2048 22527 10.0 MiB 0700
5 22528 4216831 2.0 GiB 8200 Linux swap
10 4237312 37791743 16.0 GiB 8300 Linux/Windows data
11 37791744 71346175 16.0 GiB FD00 Linux/Windows data
(gdisk continues speaking 512 B when using 4k logical sectors, which I find a
more than a little confusing)
I see no switch in gdisk for forcing 4k hardware sectors - that would be more
of a hdparm function and fairly risky. AFAIK, the translation to logical
512 B sectors is "hardwired" in the current crop of Advanced Format drives.
It might take little processing power and have little performance "impact"
The "impact" comes if a file block has to span 2 physical 4 k sectors and
partitioning via gdisk s avoids that.
Your starting point of a USB drive might be the problem. It's possible there
is some jiggery-pokery in the USB-SATA controller that you have set aside and
which did disable the translation at each start-up. It's possible that OEM
have access to some utility for that purpose. You could try going to the
Seagate web site and looking for their utiility to see whether it provides
for the translation being disabled. There were reports last year that the
then current WD USB drives could not be repartitioned - even from Windows.
Yet, as my drive ilustrates, it is not an issue with a bare SATA drive.
OTOH, gdisk does default to 4k partition sectors and that ought to give you
the performance advantage of Advanced Format by aligning to 4k physical
sectors anyway. Your remaining problem then is capacity.
Another possibilty is limitations in older SATA controllers/mainboard firmware
that might not cope with > 2.1 TB drives - perhaps try a different mainboard.
(I' m using Proliant N40L. Spec suggests it handles a max of 2 TB / drive,
but it is SATA II not SATA III - Hmm)
ISTR Rainer purchasing a 3 TB WD for his N40L recently. Perhaps he can report
his experience with it.
On Sun, 2 Sep 2012 12:00:03 linux-request at lists.samba.org wrote:
> Message: 5
> Date: Sun, 02 Sep 2012 19:36:16 +1000
> From: Eyal Lebedinsky <eyal at eyal.emu.id.au>
> To: linux at lists.samba.org
> Subject: Re: [clug] 3TB (4k sector) disk question
> Message-ID: <50432890.6000504 at eyal.emu.id.au>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> Thanks Michael,
> Yes, I tried gdisk, which is easy to use. However, it seems to inherit
> the size limit from the disk. It does not switch to 4k sectors and I do not
> see a way of telling it to do so. I also do not see a way of telling it to
> use a larger number of small sectors than the disk advertises. Note how
> 'hdparm -I' knows:
> CHS current addressable sectors: 16514064
> LBA user addressable sectors: 268435455
> LBA48 user addressable sectors: 5860533168 <<<<< 3TB of 512B
> Nevertheless gdisk uses a lower limit of 4294967294 (2TB), same as fdisk.
> What gives? Maybe Rod understands (and can explain) where the restriction
> comes from.
> On 09/02/12 19:17, Michael James wrote:
> > On 01/09/2012, at 6:49 PM, Eyal Lebedinsky wrote:
> >> 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?
> > Dear Eyal,
> > If you knew enough to partition it GPT you probably know this
> > but I hope it's worth putting put for the list.
> > The 2 TB limit is inherent in Master Boot Record (MBR/MSDOS) partitioning.
> > The field that delimits a partition doesn't have enough bits to describe
> > anything bigger.
> > Either it's not done in terms of logical blocks or you can't change that
> > anyway.
> > Modern disks actually work in 4 KB blocks, but present logically as 512
> > Byte blocks. If you partition a disk NOT on 4 KB boundaries; expect 10 x
> > less performance.
> > This is explained quite well here: http://www.rodsbooks.com/gdisk/
> > BTW Rod's gdisk partitioning tool is quite a groovy little utility.
> > Acts like fdisk, writes GPT partition tables.
> > FWIW,
> > michaelj
> Eyal Lebedinsky (eyal at eyal.emu.id.au)
More information about the linux