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New HDD Technology--Will effect Imaging Software! (Read 4076 times)
NightOwl
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New HDD Technology--Will effect Imaging Software!
Feb 4th, 2010 at 10:34am
 
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Well, here it comes....New HDD technology that will cause older imaging software to have potential problems going forward...

This new larger HDD technology is probably at the root of why with WinVista and Win7, the type of Master Boot Sector (Track) has been in transition from the old style 63 sectors.

Western Digitalís Advanced Format: The 4K Sector Transition Begins

Quote:
Advanced Format. What is it? In a nutshell, itís replacing the traditional 512 byte hard drive sector with a 4 kilobyte (4,096B) hard drive sector for a number of practical and technological reasons. Advanced Format is the name Western Digital is giving to drives implementing 4KB sectors.


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The move to 4K-sectors has been some 10 years in the making, as research in the late 90ís identified that 512B sectors made less and less sense as drives continued to get larger


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The crux of the problem is that there are 3 factors that are in constant need of balancing when it comes to hard drive design: areal density, the signal-to-noise ratio (SNR) in reading from drive platters, and the use of Error Correcting Code (ECC) to find and correct any errors that occur. As areal density is increases, sectors become smaller and their SNR decreases. To compensate for that, improvements are made to ECC (usually through the use of more bits) in order to maintain reliability. So for a drive maker to add more space, they ultimately need to improve their error-correction capabilities, which means the necessary ECC data requires more space


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At some point during this process drive manufacturers stop gaining any usable space - that is, they have to add as much ECC data as they get out of the increase areal density in the first place - which limits their ability to develop larger drives.


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to make this kind of advancement practical, a transition period is necessary. That transition period will be done through the use of 512B emulation technology, which will expose Advanced Format drives to the drive controller and operating system as having 512B sectors, when in reality they will have 4K sectors. Unfortunately, this method has a downside....


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With the emulation of 512B sectors, thereís the risk that a partition could be misaligned compared to the 4K physical sectors - where it would be unwittingly started in the middle of such a sector. As a result, the clusters of a file system on that partition would end up straddling 4K sectors, which would cause performance problems.


And, what effect will this have on imaging programs:

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The big problem is that while the first work on 4KB sectors started in 1998, it wasnít 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.


Quote:
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.


Current solutions:

Quote:
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.xxís 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 itís 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 Digitalís 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 weíd consider it the recommended solution for single-partition drives being used under Win 5.x too, as thereís no need to worry about offsets and breaking the partition table.


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The utility is available for download from Western Digitalís site, and while it isnít pretty (itís a scripted CLI application) it gets the job done.
 

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Brian
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Re: New HDD Technology--Will effect Imaging Software!
Reply #1 - Feb 5th, 2010 at 4:31am
 
@
NightOwl

Here is TeraByte's opinion. From the Newsgroup.

Quote:
For some reason many users are thinking there is something special about these new drives with internal 4K sectors and that they require "advanced formatting" to function properly.† Let me just nip it in the bud now - this is mainly marketing BS.

This should all be obvious to anyone with basic knowledge of drives/file
systems and the link.† Here's some simple brief information:

What's the deal with the 4K sectors?

A sector is the smallest unit/block of data a drive can transfer.† A traditional hard drive has used 512 byte sectors and the plan to change to a larger internal sector size has been in the works for years and now there are drives that are using 4K sectors.† The larger sector sizes allow there to be more data on the same platter because there is a gap between each sector (including the ECC data).† These drives are still fully compatibly with all existing software and operating systems because they (properly) provide a 512 byte sector view and internally handle read/writing in 4K chunks using read-modify-write.† †With proper caching technology (built into the drive) the affects of this should be negligible on typical desktops.

What about this alignment stuff?

Alignment has to do with where the partitions and data are located on the drive.† Obviously the "optimal" location is where all data to be
read/written are contained in the least number of sectors; however, it's
marketed simply as aligning partitions to the size of a sector (or block for
devices not using sectors).† The reality is you may have a more optimal
configuration or setup if the partitions are not aligned to the size of a
sector - what matters is where and how IO occurs on the drive which is
dependant on the applications (including OS) use of data, file system in
use, the file system driver implementation, and any cache manager
implementation.

On the application side of things, one given is the OS paging file which can
be heavily used by the OS.† The OS will read/write an entire page which is
4096 bytes (4K) so having that file aligned to a sector size is probably the biggest single alignment factor on a typical desktop computer.† For that file to be aligned, the clusters of the file system need to be aligned (see below).† While we're talking about the page file, if your file system
cluster size is < 4K you'd also want to ensure that the page file is not
fragmented or that could affect performance as well.

For the file systems, NTFS clusters (allocation units) occur starting at the
start of a partition so if that partition is aligned on a sector size, so
will a cluster.† For FAT the data may not be aligned even if the partition
is aligned on a sector size.† However, you can use BootIt Next Generation (BING) to format a FAT/FAT32 partition using "align for NTFS" which will be aligned; you can also use BING to align an existing FAT/FAT32 partition using its "slide" / "align for NTFS only" option.† †BING is located at
http://www.terabyteunlimited.com/bootit-next-generation.htm

However, even if a cluster is sector aligned, it doesn't mean the file
system driver is going to read/write entire clusters at a time (in fact that
would normally be a waste of time and slow file access way down).† The only time you will see that is if either the file system driver is poorly
implemented, or for security the writes on newly allocated clusters are zero padded (to end of new cluster) for security.

Another factor is a cache manager.† If this cache manager reads or writes
entire clusters (or multiple of clusters) then having a cluster aligned with
a sector size will be optimal for the cache manager and hence anything that uses it.

What's the bottom line on alignment and Windows?

Due to the cache manager and paging file it's probably best that you align
your partitions (particularly on heavy used servers/systems).† You can use BootIt Next Generation to align your new or existing partitions by enabling its Align 2048 setting (you should also disable Align on End, enable Align MBR End HS - see manual for details at
http://www.terabyteunlimited.com/support-bootit-next-generation.htm ) before creating the partition or before using its slide (move) option to move the partition location.

However, if your partitions are not aligned or you don't want to align them then simply don't worry about it because the system will continue to function.† If you find that the performance is not as expected then align them at your convenience to see if that was the cause of your performance issues.
 
 
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NightOwl
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Re: New HDD Technology--Will effect Imaging Software!
Reply #2 - Feb 5th, 2010 at 9:16am
 
@
Brian

Quote:
Here is TeraByte's opinion. From the Newsgroup.

Possible link?--I've never linked to a *newsgroup* here on the forum--is that possible--or is that something that can not be rendered on a web browser--requires one's email program to act as a reader?† (As you probably can see, I don't spend time on *newsgroups*--just can't fit it all into my schedule!!!)

This is what I love about Radified forums--there are smart people who are savvy, search the web for technology information, keep up with the ever changing information, and share it here!

I'm still wrapping my head around the new HDD technology, the new terminology, and it's effects on how imaging programs will interact (interfere?!) with creating and restoring HDD images--never mind the ongoing debate as to whether the average person will notice a performance hit vs not noticing!

To be honest--HDD's that are becoming so large--there's a tipping point where making backups of one's data (be it OS partitions or all the other data) may become an impossibly time consuming task if one is actually using and filling up those huge HDDs with programs and data!
 

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Brian
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Re: New HDD Technology--Will effect Imaging Software!
Reply #3 - Feb 5th, 2010 at 12:11pm
 
@
NightOwl

I read the newsgroup in Outlook Express but here is a web link.

http://www.terabyteunlimited.com/cgi-bin/dnewsweb?cmd=article&group=public.apps....

I can't find a link for the following...

Quote:
nothing changes because it will appear to have 512 byte sectors, otherwise it would break just about everything (making it worthless).  and yes, for those who buy into the alignment stuff, BING, IFD, etc.. already supports 1M alignment (2048 sectors) (meaning it will be aligned at all sizes up to that point).


 
 
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