What Are Advanced Format Hard Drives?
A recent change to hard drive design may cause problems for older operating systems and for dual or multi-booting.
Know Your Format.
Anyone installing or deploying an operating system or using an app that manipulates partitions would be advised to know the format of their hard drive and the capabilities of the OS and tools being used. The incorrect configuring of Advanced Format drives and partitions can lead to a performance loss. The use of an incompatible partitioning tool may result in the loss of partitions and data. Before you move on to our guide on the safe and optimum use of anything Advanced Format we hope this article might help to give you some insight into what it is all about. The main area of concern is one of partition alignment and we will try to explain with the use of a simple analogy what this is and why it matters. If you want to go on and delve into the real technical details you will find links at the bottom of this page.
What’s new about Advanced Format?
For everything to work as efficiently as intended we have to make sure that we start writing our block of data at the very top of a page so that the fixed amount of text in our block does not spill over onto a second page. If that were to happen we would have to look at two pages to read our single block of data. Pages in paper books are of course consecutive, but in computers this is not always the case so each page has to be individually indexed and referenced. Reading our single block of data from two pages is therefore going to take extra time, which if all our blocks of data spanned two pages could add up to a noticeable drop in hard drive performance, perhaps by 30% or more. So we have to align our blocks with our pages and to do this we simply have to make sure the very first page is aligned, so that all following pages are also naturally aligned. Get the first page wrong and all the following pages will be wrong.
We align things correctly by making sure that the partitions on the hard drive are created to begin at the top of one of the pages in our book. The default starting point of a traditionally created partition will not naturally line up with the start of the new larger Advanced Format page and will begin at a point inside the page where one of the smaller pages used to begin. To get our alignments correct we must therefore ensure that any app or tool we use that manipulates partitions will automatically work to the larger sector specifications, (or allow us to manually select partition settings). Old spec apps and tools should be avoided and any pre-Advanced Format operating systems we install such as WinXP should not be allowed to create their own out-of-line partitions. Conversely we need to take care when using a new spec tool or installing new operating systems on traditional hard drives. Using the new partition alignments on the old format drives should not in itself cause any issues and can in some cases be a good thing, but trying to mix partitions of both old and new alignments on the same hard drive may cause us some grief.
Using the wrong alignments or mixing alignments on a drive can cause a performance hit and may even result in some system instability. The biggest concern and issues however come during the manipulation of partitions with an app or tool that automatically works to the opposite format of any partitions that are already present on a drive. In certain circumstances one or more existing partitions may get deleted or corrupted, with of course the loss of the data they contain. A big offender is Windows' own Disk Management utility, with both the XP and Vista/7 versions of the tool being capable of deleting an opposite format partition. Some older third party tools can also have a major problem with AF aligned partitions, most notably of which is the now out-of-date and unsupported Partition Magic and Drive Image. Both will want to repair what they see as errors in Advanced Format aligned partitions, which can render them inaccessible and unbootable. No More Magic. Advanced Format and Vanishing Partitions.
Advanced Format Sectors are 8 Times Larger.
The common traditional PC hard drive has sectors that are each 512bytes in size. The first generation of the new Advanced Format hard drives have sectors that are 4096bytes in size, which will span 8 of the old sectors. In computer terms 4096 bytes translates to 4 kilobytes, or 4K, and this is why you may see Advanced Format hard drives referred to as 4K drives. You may also see them referred to as 512e hard drives, where the e stands for emulation.
Behind the Scenes Emulation.
Current mainstream operating systems and software are so ingrained in working with 512byte sectors they are unable to work directly with the larger 4k sectors. This means that a translation from one to the other has to be carried out by the firmware in the hard drive’s inbuilt controller, which results in the outside world being unaware of the 4k sectors within. The Advanced Format drive pretends to be a traditional hard drive by emulating 512byte sectors, hence the reason why AF hard drives are also sometimes referred to as 512e drives.
(Update:- The future has sneaked up on us again..... Windows-8 and Server2012 support native 4K hard drives.)
Advanced format (4K) disk compatibility update.
A hotfix rollup that improves Vista compatibility with Advanced Format hard drives.
Update that improves the compatibility of Windows 7 and Server 2008 R2 with Advanced Format.
Toshiba 12 page PDF - History and Future.
Why new hard disks might not be fun for XP users
Linux on 4KB-sector disks, Practical advice