Advanced Format Support - Optimum Performance with High Capacity Disks
Advanced Format is a new format for marking up hard drives needed to address large amounts of disk space. All manufacturers of modern hard drives, including HGST, are switching to this format.
One of the main features of Advanced Format is the increase in sector size from 512 to 4096 bytes. To maintain compatibility with programs designed for the previous format, the new drives have an emulation mode called “512e”.
Most modern operating systems support Advanced Format. To achieve optimal I / O performance, it is necessary that the disk partitioning is carried out correctly, and that data is recorded in 4-kilobyte blocks by both the operating system and application programs. The latest operating systems by default fulfill all the conditions necessary for effective work with Advanced Format. If you use older software, special utilities may be required to configure the disk subsystem for optimal performance.
Advanced Format Device
In the middle of Figure 1, eight consecutive 512-byte sectors are depicted. In addition to user data, each sector contains service information: markup data and error correction code. When replacing eight 512-byte sectors with one 4-kilobyte sector, the amount of overhead needed is reduced (see the bottom of the figure). Thus, when working with large files (and the average file size compared to the times when the 512-byte format was used, it grew), the disk space is used more efficiently. In addition, more space is allocated for the error correction code, which ensures better data integrity.
Fig. 1. Comparison of 512-byte and 4-kilobyte formats (1).
Compatibility
A significant part of the hardware and software in use are designed for a sector size of 512 bytes and expect that data will be sent in 512-byte blocks. Emulation of such an exchange is implemented in new disks at the interface level. When asked to read a block, the disk reads the entire sector (which does not take a lot of time) and transfers only the necessary block to the program. If the program receives a request to write the block, the disk reads the whole sector, puts the received block into it and overwrites the whole sector (see Fig. 2). Between reading and writing, time passes, the disk can make several revolutions during this time.
Fig. 2. In emulation mode when writing 512-byte block first reads the disk sectors, puts it in the block, and then writes the sector
Providing speed
To achieve the highest performance, it is necessary that the recording format on the disc matches the format of the disc. Ideally, recording should be done in 4 kilobyte blocks and each block should be written in one sector. This condition is fulfilled if both the operating system and application programs are configured to work with 4-KB blocks, and the disk partitioning is performed correctly.
Most modern operating systems use file systems in which disk space is allocated in 4-kilobyte blocks, or clusters. A 4-kilobyte block corresponds to eight 512-byte sectors (see Figure 3).
Fig. 3. Correspondence of the cluster to the sector in emulation mode.
Partition Alignment
When using operating systems that record data in 4-kilobyte clusters (most modern operating systems), it is important that their boundaries are aligned with the boundaries of the disk sectors. In 512e emulation mode, a drive cannot prevent a partition from being placed in a block whose number is not a multiple of eight. If this happens, one cluster will be located in two sectors (see Fig. 4). Thus, when reading or writing a 4-kilobyte cluster, you will need to read or write 8 kilobytes, respectively - twice as much. And if, when reading, the difference in speed will not be large, then when recording it will be noticeable.
Fig. 4. Placement of a cluster not from the beginning of the sector.
Advanced Format Operating Systems
In the following operating systems, the cluster size is 4 KB, and during installation the disk partitioning is performed correctly:
• Microsoft Windows Vista SP1 and newer;
• Microsoft Windows 7;
• Microsoft Server 2008;
• Mac OS X 10.4 and later;
• Linux Ubuntu 8.04+, SUSE, Linux kernel 2.6.34+ (you must use Linux Partitioning Utility).
Operating systems that do not automatically match clusters to sectors:
• Microsoft Windows XP;
• Microsoft Server 2003;
• Microsoft Windows Home Server V1.
HGST Align Tool
To fix the logical partitioning of disks whose partitions are not aligned on the borders of sectors, you can use the utility released by HGST for Windows. It can be downloaded at www.hgst.com/support/downloads .
In addition, Advanced Format is supported by a number of third-party disk utilities:
Disk Partitioning Tools
For Linux:
GPARTED 2.1+ (with -a optimal or -a minimal options).
www.gnu.org/software/parted/manual/parted.html
For Windows:
Acronis Disk Director Home 11 or Paragon Partition Manager 11.
For Mac:
Disk Utility (included with Mac OS X 10.4+), creates a GPT partition (GUID Partition Table).
Additional information:
www.idema.org (Advanced Format documents, including specifications)
en.wikipedia.org/wiki/Advanced_Format
www.t13.org , document: ATA8-ACS (ATA Command Set)
www.t10.org , document: SBC -3 (SCSI Block Commands)
Microsoft Windows 7 and Advanced Format Hotfix (KB981208):
support.microsoft.com/kb/982018
Intel Rapid Storage Technology (RST): www.intel.com/support/chipsets/imsm/sb/CS -031502.htm
(1) Hereinafter, figures are taken from the Hitachi Advanced Format Technology Brief - www.hgst.com/tech/techlib.nsf/techdocs/3D2E8D174ACEA749882577AE006F3F05 $ file / AFtechbrief.pdf
One of the main features of Advanced Format is the increase in sector size from 512 to 4096 bytes. To maintain compatibility with programs designed for the previous format, the new drives have an emulation mode called “512e”.
Most modern operating systems support Advanced Format. To achieve optimal I / O performance, it is necessary that the disk partitioning is carried out correctly, and that data is recorded in 4-kilobyte blocks by both the operating system and application programs. The latest operating systems by default fulfill all the conditions necessary for effective work with Advanced Format. If you use older software, special utilities may be required to configure the disk subsystem for optimal performance.
Advanced Format Device
In the middle of Figure 1, eight consecutive 512-byte sectors are depicted. In addition to user data, each sector contains service information: markup data and error correction code. When replacing eight 512-byte sectors with one 4-kilobyte sector, the amount of overhead needed is reduced (see the bottom of the figure). Thus, when working with large files (and the average file size compared to the times when the 512-byte format was used, it grew), the disk space is used more efficiently. In addition, more space is allocated for the error correction code, which ensures better data integrity.
Fig. 1. Comparison of 512-byte and 4-kilobyte formats (1).
Compatibility
A significant part of the hardware and software in use are designed for a sector size of 512 bytes and expect that data will be sent in 512-byte blocks. Emulation of such an exchange is implemented in new disks at the interface level. When asked to read a block, the disk reads the entire sector (which does not take a lot of time) and transfers only the necessary block to the program. If the program receives a request to write the block, the disk reads the whole sector, puts the received block into it and overwrites the whole sector (see Fig. 2). Between reading and writing, time passes, the disk can make several revolutions during this time.
Fig. 2. In emulation mode when writing 512-byte block first reads the disk sectors, puts it in the block, and then writes the sector
Providing speed
To achieve the highest performance, it is necessary that the recording format on the disc matches the format of the disc. Ideally, recording should be done in 4 kilobyte blocks and each block should be written in one sector. This condition is fulfilled if both the operating system and application programs are configured to work with 4-KB blocks, and the disk partitioning is performed correctly.
Most modern operating systems use file systems in which disk space is allocated in 4-kilobyte blocks, or clusters. A 4-kilobyte block corresponds to eight 512-byte sectors (see Figure 3).
Fig. 3. Correspondence of the cluster to the sector in emulation mode.
Partition Alignment
When using operating systems that record data in 4-kilobyte clusters (most modern operating systems), it is important that their boundaries are aligned with the boundaries of the disk sectors. In 512e emulation mode, a drive cannot prevent a partition from being placed in a block whose number is not a multiple of eight. If this happens, one cluster will be located in two sectors (see Fig. 4). Thus, when reading or writing a 4-kilobyte cluster, you will need to read or write 8 kilobytes, respectively - twice as much. And if, when reading, the difference in speed will not be large, then when recording it will be noticeable.
Fig. 4. Placement of a cluster not from the beginning of the sector.
Advanced Format Operating Systems
In the following operating systems, the cluster size is 4 KB, and during installation the disk partitioning is performed correctly:
• Microsoft Windows Vista SP1 and newer;
• Microsoft Windows 7;
• Microsoft Server 2008;
• Mac OS X 10.4 and later;
• Linux Ubuntu 8.04+, SUSE, Linux kernel 2.6.34+ (you must use Linux Partitioning Utility).
Operating systems that do not automatically match clusters to sectors:
• Microsoft Windows XP;
• Microsoft Server 2003;
• Microsoft Windows Home Server V1.
HGST Align Tool
To fix the logical partitioning of disks whose partitions are not aligned on the borders of sectors, you can use the utility released by HGST for Windows. It can be downloaded at www.hgst.com/support/downloads .
In addition, Advanced Format is supported by a number of third-party disk utilities:
Disk Partitioning Tools
For Linux:
GPARTED 2.1+ (with -a optimal or -a minimal options).
www.gnu.org/software/parted/manual/parted.html
For Windows:
Acronis Disk Director Home 11 or Paragon Partition Manager 11.
For Mac:
Disk Utility (included with Mac OS X 10.4+), creates a GPT partition (GUID Partition Table).
Additional information:
www.idema.org (Advanced Format documents, including specifications)
en.wikipedia.org/wiki/Advanced_Format
www.t13.org , document: ATA8-ACS (ATA Command Set)
www.t10.org , document: SBC -3 (SCSI Block Commands)
Microsoft Windows 7 and Advanced Format Hotfix (KB981208):
support.microsoft.com/kb/982018
Intel Rapid Storage Technology (RST): www.intel.com/support/chipsets/imsm/sb/CS -031502.htm
(1) Hereinafter, figures are taken from the Hitachi Advanced Format Technology Brief - www.hgst.com/tech/techlib.nsf/techdocs/3D2E8D174ACEA749882577AE006F3F05 $ file / AFtechbrief.pdf