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Do More High-Capacity Storage Readiness

Answers to frequently asked questions about what key elements must be enabled for hard drive storage capacities over 2.1TB

This FAQ answers frequently asked questions about what key elements must be enabled for hard drive storage capacities over 2.1TB.

What are the key elements that must be enabled for storage capacities over 2.1TB?

It depends on whether or not you would like the drive to be bootable, and if you will be using a Host Bus Adaptor (HBA) or RAID controller. A summary of the requirements based on your intended design is shown in Table 1.

What is long LBA addressing?

Long LBA addressing defines extended Logical Block Addresses (LBAs) in order to support hard drives larger than 2.1TB. Long LBA addressing increases the number of bytes used to define the LBA in the Command Descriptor Block (CDB). System must support at least 16-byte Command Descriptor Blocks (CDBs) or 32 bytes (Protection Information commands only) and Dynamic Sense Data to access the LBA counts above 2.1TB. Eight LBA address bytes are provided in16- and 32-byte CDBs. This is a doubling of the 4 bytes in 10-byte commands.

What if my system does not support long LBA addressing?

Systems without long LBA addressing support cannot access the full HDD capacity. It will see any drive greater than 2.1TB as only 2.1TB. Or it may recognize only the storage space over 2.1TB. For example, Windows XP would see a 3TB hard drive as only a 990GB drive!

What do I need to do to prepare for >2.1TB?

Refer to Table 1 to evaluate your design needs. In general, you need to examine support from your OS, your system BIOS, your HDD device driver and/or your HBA/RAID controller and drivers.

How do I support >2.1TB on legacy systems?

For enterprise solutions using RAID controllers, you must use Mode Select to de-stroke the hard drive to match the capacity of the legacy system. A Mode Select CDB, with either a short or long block descriptor, can be used to reduce the drive to a legacy capacity. Then all legacy commands will work normally.

If you are not using an HBA or RAID controller, and your operating system does not support long LBA addressing, you will not be able to address the entire HDD capacity.

How do I support >2.1TB on new systems that support >2.1TB?

For RAID controllers and HBAs that support this feature, enable the D_SENSE bit to support the larger capacity. Use all new 16-byte CDBs.

For desktop or workstations without an HBA, you must create HDD partitions using the GUID Partition Table (GPT) option available with Windows Vista and Windows 7. If you would like the entire drive to be seen as a single bootable partition, you will also need to have a Unified Extensible Firmware Interface (UEFI) BIOS. Refer to Table 1.

What are the limitations to my storage solution if these elements are not enabled?

Your system won’t be able to see the full capacity of the drive. In most cases, you will only have access to the first 2.1TB of data on the drive, rendering the rest of the drive inaccessible.

Does it matter if the high-capacity drive is a primary bootable drive or a secondary drive in a desktop or enterprise environment ?

Yes. Different limitations apply.

In a secondary drive (non-bootable drive) solution, Windows Vista or Windows 7 OS is required (Windows XP is not capable of >2.1TB), and a GUID Partition Table (GPT) is required. Legacy Master Boot Record (MBR) partitions are limited to 2.1TB in size.

In a primary drive (bootable drive) solution, in addition to the Windows operating system compliance and the GPT requirements noted above, a Unified Extensible Firmware Interface (UEFI) BIOS is required (older BIOS do not include support for drives >2.1TB; updated BIOS with UEFI support for this purpose are in development), and an HDD driver support for >2.1TB hard drives is required.

Updates to standard HDD drivers are being modified and tested. The standard Windows driver is ready and Intel is testing modifications.

Many servers ship with UEFI BIOS, so these systems can boot from a disk volume >2.1TB. However, a very common configuration for servers is to boot from a low-capacity SATA drive and use the RAID volumes as secondary volumes.

Are there additional concerns for an enterprise RAID environment?

Yes, in addition to the requirements noted above, the RAID controller must support the >2.1TB hard drives with an HDD driver that is long LBA addressing-enabled. It is highly recommended that you check with your RAID controller manufacturer for >2.1TB-enabled driver support.

Has Seagate tested any of the RAID controllers or HBAs for support of hard drives >2.1TB?

Some initial testing has been completed. Contact your Seagate sales representative for confirmation on your particular RAID controller or HBA. This information should be verified with your RAID controller or HBA manufacturer before proceeding.

Figure 1: Requirements Summary

Second Drive (non-bootable) Solution Desktop, Workstation
Requirement Explanation
Long LBA-capable Operating System(Windows Vista, Windows 7 or modified Linux XP is not capable of >2.1TB
GUID Partition Table (GPT) required Legacy Master Boot Record (MBR) partitions are limited to 2.1TB in size.
Primary Drive (bootable) Solution Desktop, Workstation
Requirement Explanation
Long LBA-capable Operating System(Windows Vista [64-bit], Windows 7 [64-bit] or modified Linux) XP is not capable of >2.1TB
GUID Partition Table (GPT) required Legacy Master Boot Record (MBR) partitions are limited to 2.1TB in size.
A unified Extensible Firmware Interface (UEFI)BIOS is required for bootable drives >2.1TB Older BIOS do not include support for drives >2.1TB. Updated BIOS with UEFI support for this purpose are in development.
HDD driver support for >2.1TB hard drives Updates to standard HDD drivers are being modified and tested. The standard Windows driver is ready and Intel is testing modifications.
Storage Server or Storage Array Solutions
Requirement Explanation
Confirmed HBA or RAID controller support for long LBA-addressing Controllers manage the HDD addressing
Mode Select to de-stroke drive for use with legacy Legacy controllers do not support long LBA-addressing

 

What is Seagate doing to help ensure compatibility?

In addition to our ongoing interoperability testing with industry-leading RAID controller/HBA manufacturers, Seagate is attending the UEFI Plugfest in June 2010 to test compatibility with all willing participating component manufacturers. For more information on UEFI, go towww.UEFI.org.

What Seagate products are planned in support of capacities in excess of 2.199TB?

The initial 3TB introduction from Seagate will focus on a branded external drive, as limitations associated with hard drives larger than 2.1TB can be managed in external HDD configurations without the involvement of any third party. General release of core HDDs greater than 2.1TB is planned for Fall 2010 when a wider variety of system compatibility is expected.

What are our competitors doing?

Seagate competitors will experience the same issues with any HDDs over 2.1TB that they bring to market.

Seagate continues to lead the market and our high-capacity solutions are no exception. Seagate continues to work closely with eco-system partners to ensure end-to-end compatibility for our mutual worldwide base of customers.

For More Information

Read the Seagate technology paper, Deploying the Next Generation of High-Capacity Hard Drives: Overcoming Legacy Storage Architecture Limits With Hard Drives Larger Than 2.1TB, TP614.

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