What Operating Systems Are Affected

Now that we’ve dealt with what 4K sectors are, why Western Digital and other drive manufacturers are switching to them, and what the potential pitfalls of 512B emulation are, we can look at the specific cases where there are potential problems.

The big problem is that while the first work on 4KB sectors started in 1998, it wasn’t until after the launch of Windows XP that the matter came to a head. As a result the 5.x versions of Windows (2K, XP, 2K3, WHS) have no concept of 4KB sectors. Even though all operating systems will be seeing 512B sectors through the use of emulation technology on the drive controller, out of Windows only Win 6.x (Vista, 2008, Win7) and later have been programmed to take in to account the alignment issues we mentioned earlier. Win 5.xx in particular has a nasty habit of starting the first partition at LBA 63, which is 1 512B sector misaligned from a 4K sector boundary. In essence, the issue is that Win 5.x will always create a misaligned first partition and will have poor default performance as a result.

Although Win 5.x is the primary victim here, other versions of Windows can also be affected in edge cases. Along with the need for 4K-aware operating systems, drive imaging software needs to be 4K-aware. Otherwise such imaging software may inadvertently create misaligned partitions too. As such, Win 6.x is also affected by alignment issues when imaging software is used, as some (and perhaps all?) imaging products currently available will write misaligned partitions and/or clusters.

Notably, Linux and Mac OS X are not affected by this issue. Western Digital has tested both of these operating systems, and officially classifies them as not-affected. Ultimately we suspect that if you went back far enough you could find older versions of these OSes that are affected, but unlike Win 5.xx, there’s not a significant legacy user base to worry about. Along these lines, Linux and Mac OS X drive imaging products are similarly unaffected. In their testing, imaging tools such as SuperDuper didn’t run in to any alignment issues, so Linux and Mac OS X users are not affected in any way by 4K sectors. It’s only Windows and Windows imaging products that are affected.

In order to solve the misalignment issue, Western Digital is offering two solutions. The first solution for correcting misaligned partitions is specifically geared towards Win 5.x, and that is an option on the drive itself to use an offset. Through the jumpering of pins 7 and 8 on an Advanced Format drive, the drive controller will use a +1 offset, resolving Win 5.xx’s insistence on starting the first partition at LBA 63 by actually starting it at LBA 64, an aligned position. This is exactly the kind of crude hack it sounds like since it means the operating system is no longer writing to the sector it thinks its writing to, but it’s simple to activate and effective in solving the issue so long as only a single partition is being used. If multiple partitions are being used, then this offset cannot be used as it can negatively impact the later partitions. The offset can also not be removed without repartitioning the drive, as the removal of the offset would break the partition table.

The second method of resolving misaligned partitions is through the use of Western Digital’s WD Align utility, which moves a partition and its data from a misaligned position to an aligned position. This is the recommended solution for using multiple partitions under Win 5.xx, along with correcting any misaligned partitions generated by imaging software. For that matter we’d consider it the recommended solution for single-partition drives being used under Win 5.x too, as there’s no need to worry about offsets and breaking the partition table.

The utility is available for download from Western Digital’s site, and while it isn’t pretty (it’s a scripted CLI application) it gets the job done. The amount of time needed to run the utility is based on the amount of data that needs to be moved rather than the partition size (it simply ignores empty space), so it’s best to run the utility immediately after creating a partition or installing Windows, as there’s less data to move around.

Unfortunately, at this point the utility also serves as the only way to identify an Advance Format drive without physically looking at it. Looking at the ATA spec, it looks like there’s a provision for asking a drive its native sector size (regardless of 512B emulation) but at this point there’s no such tool beyond the WD Align utility itself. This in and of itself isn’t a big issue, but if you’re a techie that ever finds themselves working on an XP machine with a 1TB+ Western Digital drive, you’ll want to keep an eye open.

The First Drives & The Future

So what are the first Advanced Format drives and when are they due? The first drives will be Caviar Green drives using multiple 500GB platters – so the 1TB, 1.5TB, and 2TB Caviar Green. These drives will be shipping any day now, and can be identified through two different methods: 1) They all have 64MB of cache - the first WD Caviar Green drives to come with that much cache - and 2) They all have EARS in the drive model number, e.g. WD10EARS.

As we stated before, in spite of the benefits of 4K sectors, Western Digital is not pushing these drives as part of any major product launch. Rather they’re going to be quietly trickling in to the marketplace. Expect a price premium at first (as with any other new product) before settling down. We don’t have a drive on-hand to review, but from the fact that this is a low-key launch, WD isn’t painting any expectations of a performance difference, although this will be something to test in the future.

And on that note, expect to see similar launches from everyone else within the next year. The last IDEMA plan called for everyone to have 4K-sector drives by 2011, so everyone should be launching within the next year here. Everyone using 512B emulation is going to run in to the same teething issues with Win 5.x – so while other vendors may handle things slightly differently, ultimately everyone is going to be compensating for Win 5.x in some manner (in case it hasn’t been made clear here, these guys would be ecstatic for Win 5.x to go away quickly).

Farther down the road will be the exposure of 4K-sectors to the operating system itself. Linux and Win 6.x are set (and we believe that Mac OS X is too), the only limit right now is the desire to do a phased transition to make thing easier for legacy users. Since 4K-sector drives won’t work on Win 5.x at all, drive manufacturers can’t put them on the market so long as there’s a significant legacy base. 2014 – the year that extended support ends for WinXP – looks like a good year to finally complete the move to 4K sectors.



View All Comments

  • dragonf - Monday, November 8, 2010 - link

    Correct me if I am wrong, but after reading this article on 4k sectors:
    I assume that it is possible to align Advanced Format drives (those ones, which are not provided with a special aligning software by HD manufacturer) for Windows XP usage with 3rd party 4k-aware partitioning utility:
    "The most critical aspect of a smooth and successful transition to 4K sectors used in Advanced Format is to promote the use of 4K-aware hard drive partitioning tools."
    "When using third-party software or utilities to create hard drive partitions, check with your vendor to make sure they are updated and confirmed to be 4K aware."

    So to align properly for Win XP usage for example Samsung 2TB F4EG HD204UI one has to find a 3rd party software tool for partitioning, which is 4k-aware, and use that software to partition such disk instead of Windows XP Disk Manager.

    Are there any free 4k-aware partitioning tools for Windows XP?

    Also would re-aligning utilities provided by WD and Seagate work with other manufacturers HDs like Samsung?

    From that article I learnt also that even the newer OSes like Windows 7 do not use 4k sectors directly, they still have to use 512 B sectors. Those newer systems are only capable of aligning Advanced Format hard drives properly during their partitioning, without the need to use 3rd party 4K-aware partitioning software, and that's all:
    "there are many aspects of modern computing systems that continue to assume that sectors are always 512 bytes. To transition the entire industry over to the new 4K standard and expect all of these legacy assumptions to suddenly change is simply not realistic. Over time, the implementation of native 4K sectors, where both host and hard drive exchange data in 4K blocks, will take place. Until then, hard drive manufacturers will implement the 4K sector transition in conjunction with a technique called 512-byte sector emulation."

    "The sector size increase, described by Advanced Format, occurs at the hard drive media level. Host systems will continue to request and receive data from the hard drive in 512-byte sector sizes. However, the translation from 4096-byte sectors in the hard drive to the 512-byte sectors in the host will be managed in the hard drive. This process is called 512-byte emulation. It’s important that every drive partition start with an LBA offset that is aligned to the drive’s physical 4K sector. If partitions are un-aligned, then hard drive performance will be degraded."
    "How can partition misalignment conditions be managed?
    The first management step is to avoid misaligned conditions in the first place. This can be achieved by creating hard drive partitions with a 4K aware version of your operating system or through a hard drive imaging software product."
    "The second method to managing misaligned partitions is to use partition-alignment software to identify and fix misaligned partitions. This technique should be used during the hard drive integration process."

    "It’s not practical to make host computer systems talk in 4K native language – at least for a while. There are just too many places the 512 byte assumption is embedded. So, while hard drives will transition to 4K sectors physical sectors on the media, they will still “look and talk” like 512 byte formats to host computers. They will actually emulate 512 byte communications to hosts. This works well as long as the logical 512 byte assumptions from the host computer are aligned with the 4K sectors on the hard drive."
    "It turns out that when a hard drive partition is created, the starting position can vary. A 4K drive format is set to work under the assumption that the first 512 byte sector (Logical Block Address = 0) will align perfectly with the first physical 4K sector".
    "Alignment 0 ... works well for hard drives & 512 byte emulation because they can neatly map eight 512 byte logical blocks into a single sector. Sometimes hard drive partitions get created so the logical to physical alignment is off...".
    "This is called Alignment 1 and it’s not so good for 4K drives when it comes to emulating 512 byte legacy sectors, especially when writing data. Essentially, this alignment can often cause a hard drive to manage a write with extra disc rotations, which slows things down. The results can be sort of dramatic as shown by these test results at HOTHARDWARE.com"
    "The Windows XP situation seems fairly well understood in the marketplace. What is much less understood is the situation with cloning and imaging software. System builders, integrators and IT organizations frequently rely on these tools to configure systems for sale or deployment in their organization. Even if you are using Windows Vista or Windows 7, if your hard drive was partitioned with one of these utilities, you’re likely to end up with an un-aligned partition with the potential for poor performance."

    Video on 4K sectors:
    Seagate manages aligment problems in the background without any interaction or knowledge of user.

    BTW, a warning against 2TB hard drives:
  • imwithid - Sunday, November 14, 2010 - link

    There seems to be much confusion and I feel as though I'm being thrown in. This seems to be, as far as I've been able to find, an x86 issue for XP users (not sure about Vista or 7). For those running Windows XP x64 Edition, this software layer interface to firmware level should not be an issue when it comes to alignment.

    That said, however, I suspect that Windows XP x64 Edition still formats a new, raw unformatted hard drive into 512 bit sectors during install, thereby requiring either an external live CD or boot CD that can properly format the drive's partition sector mapping into the 4096 bit Advanced Format that exists at the firmware level. Otherwise, the alignment problem will appear as the partition addresses may attempt to locate a sector at a point partway into the larger section.

    Can anyone confirm this?
  • airesearch - Wednesday, January 5, 2011 - link

    I have two new un-partitioned 1TB Black WD drives that I'll be using for data storage. Even though they don't indicate Advanced Formatting on them, If I partition them for 4k sectors and quick format them at 4096 allocation unit size will they work ok with XP PRO SP2? Reply
  • bobbozzo - Monday, March 14, 2011 - link

    "Farther down the road will be the exposure of 4K-sectors to the operating system itself. Linux and Win 6.x are set (and we believe that Mac OS X is too), the only limit right now is the desire to do a phased transition to make thing easier for legacy users. Since 4K-sector drives won’t work on Win 5.x at all, drive manufacturers can’t put them on the market so long as there’s a significant legacy base. 2014 – the year that extended support ends for WinXP – looks like a good year to finally complete the move to 4K sectors."

    It's already happening...
    I just bought a 3TB Western Digital My Book Studio LX, Model WDBACH0030HAL-NESN. I chose this drive in because I wanted Firewire (it also has USB), and I did not want to go with the Seagate dockable drives due to reports (here) of overheating (the WD LX is in an well-ventilated aluminum case).

    Many websites are listing this drive as compatible with Windows XP, so I ordered it from Amazon.

    The box says "formatted for Mac OS X"... and "requires reformatting for Windows XP, Vista, or 7".
    In much smaller print, it says "Windows XP does not support drives with capacities greater than 2TB".
    I took that to mean that I can't create a partition over 2TB, which I expected anyways.

    Upon connecting the drive to an XP PC, a 'virtual CD' was mounted with utilities. I ran the quick format utility, but it eventually fails saying something like "the sector size cannot be changed with your firmware version".

    After fruitlessly searching for help, I called WD and they eventually told me this drive is not supported in XP, and there is no way to adjust the sector size or enable translation.

    The primary purpose of this drive was to take an image of a Win2003 server using VMWare Converter from a laptop running XP. This turned out to be impossible, but I was able to put a firewire card in the server (it only had USB1.0) and make an image directly.

    However, after that was done, I was planning to use this drive to backup my PCs, most of which are running XP.
    I have one machine running Win7 but it does not have Firewire; I may have to buy a firewire card.
    My PC at work is also XP, so there will be no way to use this drive to move data from home to work.

    I am also disappointed that no major-brand 2-3tb drives seem to exist with 2 or more of the following:
    USB 3

    I know it's possible because some of the external case manufactures make cases with USB 2, eSATA, and Firewire 800 in on, but I've had too many bad experiences with third-party cases (poor ventilation, failed fans, failed power supplies, weak plug connections, ...)

    Seagate comes close with their docks, but the base model is USB 3 only, and additional docks are $30-50 EACH, and they are bulky to carry around.

    FYI, at least one MAC website lists this drive as being a NAS as well as having Firewire, but that is incorrect. From the pictures, however, it was impossible to tell as the Firewire 800 ports are indistinguishable from CAT5 in small pictures.
    Also, the USB port is a mini-USB so one has to always carry an (included) cable around with it if one wants to use USB.

    Perhaps one day USB 3 will be the only connector we need for external storage, but I've had bad experience with high CPU usage on USB 2 and I don't see any evidence that USB 3 is better (still no DMA).

    Thanks for the informative article, btw.

  • James5mith - Friday, May 27, 2011 - link

    This article, and the 4K "conversion" has been happening for some time, and yet I have still been unable to find 4K native devices.

    I'm interested to see a rundown of what is and isn't possible with 4K drives, if there is any kind of throughput benefits and/or IOPS benefits, etc.

    Do you know of anything coming within the next 6 months or so?
  • alpinemobile - Saturday, October 22, 2011 - link

    Advanced Format Drive Fix for Windows XP (Solution, workaround).
    After reading a lot of crap about Advanced Format drives having problems with Windows XP and other old OSes, I decided to post this easy fix. So if you want to use the Advanced Format Drive with other OSes than Vista or 7 do this one easy thing after you purchase the drive.
    Create all the partitions on the disk using Acronis Disk Director 11 (or later). Remember to tell Acronis Disk Director that you'll be using the drive for Windows 7, even though you'll use it for XP or other OS. Do not use any obsolete partitioning tools like Acronis Disk Director 10 or Windows XP disk management! The old partitioning tools will create the partitions misaligned!
    That's all you have to do!
    You can do a test and see if you have done everything right by running this utility: Dell Utility Advanced Format HDD Detection Tool. Just Google it.
    You'll see whether your partitions are Aligned or Misaligned.
    If you delete a partition using Windows XP and recreate it using Windows XP it will be misaligned again.
    So use Acronis Disk Director 11 to recreate it and everything will be fine again.

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