User:Rpeters

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this is it -Rpeters13:25, 24 August 2012 (EST) --

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For General Users

Overview

Advanced Format (AF) Hard Disk Drives are used in many pre-built computers and USB drives from about 2011 onwards.. By way of explanation

• AF drives have 4 kB hard sectors in lieu of
• the traditional 512 B sectors

Advantages

• much faster (less disk overhead)
• more space efficient (larger disk capacity from same hardware)
• overcomes immutable capacity limit of ~2.19 TeraByte for conventional drives

Disadvantages

• Windows 32 bit systems cannot boot from AF drives
  • requires driver from HDD manufacturer, to use as data only internal drives

No action is required by the typical purchaser, because the manufacturer will have taken care of the special formatting required with AF drives. Getting Technical below, provides guidelines for those needing to:

• repartition drives
• install new, "bare" drives

Getting Technical

Advanced Format Drives

New HDD from about 2011 onwards are likely to be Advance Formatted

• usually pre-formatted
• likely to be stated on drive or packaging
• essential for drives over 2.1 TeraByte capacity
• has been used on new drives as small as 250GB

Avoid reformatting drives to MBR

• performance loss of up to 40% if reformatted MBR
• requires special procedure - see "Strictly for Geeks" below

. A new type of partition table called Globally Unique Identifier(GUID) Partition Table (GPT) is required to optimise the performance of AF disks. The partition table previously in common use has no univerwsally agreed name but is given the nomenclature Master Boot Record (MBR), because that was a unique feature of it.

Legacy partitioning tools do not handle GPT. A suitable tool for intermediate users is "parted" or its GUI front-end "gparted". The simplest way to use these is from a bootable utility CD

http://www.sysresccd.org/Download http://partedmagic.com/doku.php?id=downloads

Altering Partitions

It is not advisable to delete or alter patitions of type ef01 or ef02, because these have a special purpose in GPT. Other partitions may be re-sized or added, as required. Note that:

• all partitons in GPT are Primary
• up to 128 primaries are permitted
• GPT has no concept of "Extended" or "Logical" partitions.
• partition type numbers sometimes differ from those used with MBR partition tables

A compleat description of GPT is available at:

http://www.rodsbooks.com/gdisk

New Drives

The full capacity of Drives over 2.1 TB can be utilised only via recent mainboards or add-on SATA controllers

• support for SATA 3 (aka 6 Gb/sec) is required

The boot flag in GPT does *not* make a disk bootable from a BIOS mainboard. See the procedures at:

http://www.sysresccd.org/Sysresccd-Partitioning-EN-The-new-GPT-disk-layout

Strictly for Geeks

Capacity

The international standard for data capacity uses multipliers of 2 ^ 10 in lieu of SI decimal multipliers of 10 ^ 3 eg

• kiB = 1024 Bytes
• kB = 1000 Bytes

through

• TiB = 2.198 TB

Why does this matter ?

1. drives have always had sectors that are multiples of kiB
   • 0.5 kiB for conventional HDD
   • 2 kiB for CD & some Magneto Optics
   • 4 kiB for AF drives
   • 32 kiB for DVD
2. advanced formatting tools allocate partitions in MiB, GiB, TiB increments
   • partition sizes will be reported larger by older OS
   • formatted capacity of a drive will be somewhat less than manufacturer's nameplate rating, which is usually in decimal
3. advanced formatting tools might align partitions on MiB boundaries
   • helps optimise performance

Tools

A more capable partitioning tool is required to set up the advanced features of GPT. The partitioning tool gdisk is downloadable from http://www.rodsbooks.com/gdisk/download.html

Partition Conversion

MBR drives can be converted to GPT partition table, without erasing data, subject to some limitations and risks

• essential to backup data & system files
• use the "r" menu option in gdisk, followed by "g"
• some partition numbers might be changed

Advanced Patitioning Layouts

• non-sequential partition numbering
• spaces between partitions
• partition alignment on 1 MiB boundaries

Re-formatting

Drives up to 2.1 TB,manufactured during the transitional period, logically divide each 4kB sector into eight 512 B sectors

• permits partitioning using legacy programs
• deprecated because doing so can decrease performance up to 40%
  • essential for boot drives in Windows 32 bit systems

AF drives that are re-formatted to MBR might behave unreliably unless expert options in gdisk are used

• see "z" menu option