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Windows 7: Partition Wizard: Win7 non-compliant, Advance Format drive mis-aligned


03 Feb 2012   #1

Window 7 Home Premium 64-bit
 
 
Partition Wizard: Win7 non-compliant, Advance Format drive mis-aligned

Abstract
--------
Partition Wizard doesn't seem to be compliant with the partition scheme of Window 7. Partitions created by Partition Wizard are not aligned with the beginning of 4 KiB physical sectors in Advanced Format drives/volumes, thereby leaving open the possibility for a significant degradation in drive performance. Furthermore, the location of the Master File Table in volumes created by Partion Wizard doesn't seem to follow Window 7's scheme either; Partition Wizard seems to put the MFT at the very beginning of the volume.


Some tech data first:
======================================================================

OS: Windows 7 Home Edition, 64 bit version

Tech info of those drives under test
------------------------------------
-> 2TB external USB 3.0 data drive under test (4 KiB physical sector drive; Advanced Format).
-> 1TB internal system drive with OS Windows 7 (512 byte physical sector drive; Standard Format).

Abbreviations
-------------
Disk Managment in Windows 7 = DM
Partition Wizard (any of the following two releases) = PW
Partition Wizard Installed on Windows 7 = PWWin7 (Free version)
Partition Wizard Boot CD = PWBootCD
Advanced Format drive = AF drive

Download site
-------------
Best Free Partition Manager Freeware for Windows 7, Windows Vista, and Windows XP 32 bit & 64 bit. MiniTool Free Partition Manager Software Home Edition.
Partition Wizard Bootable CD allows user to boot computer directly to manage partition.

UltraDefrag 5.0.2: for visualizing the volume cluster layout, and $MFT position:
UltraDefrag - An Open Source Defragmenter
Download:
https://sourceforge.net/projects/ult...release/5.0.2/

PartitionInfo version 8: for determining start sectors and size (in sectors) of volumes.
Download: go to
ftp://ftp.symantec.com/public/englis.../pq/utilities/
and download PartInNT.zip .

Also pdedit.zip from the same ftp site could be usable, although, it did not work on my Windows 7; all ok however on WinXP.

Partition scheme in Windows 7
------------------------
Advanced Format drives have 4 KiB physical sectors but emulate 512-byte logical sectors in their communication, Apparently, Windows 7 cannot handle 4 KiB native physical sector drives (as far as I understood).

In order to eliminate the risk of partition mis-alignment with respect to the beginning of the 4KiB physical sectors of the drive, DM in Windows 7 uses an offset of 1 MiB (1,048,576 bytes) when creating partitions (that offset can be changed in the registry). Hence that the distance between the MBR and the first partition, distance between any partitions (primary and logical), distance between EPBR and beginning of its logical partition, is always 1 MiB. Note that 1 MiB = 2048 logical sectors and 4 KiB = 8 logical sectors, where a logical sector = 512 bytes.

If dividing the start sector of a volume by 2048 results in an integer, then the start sector of the volume is Windows 7 compliant; start_sector/2048 = integer -> OK. If the start_sector/2048 = integer, then start_sector/8 = integer automatically and the volume is aligned with the beginning of the 4KiB physical sectors; the latter I call 4KiB aligned.

If start_sector/2048 = non-integer, then the volume is Windows 7 non-compliant but can still be 4KiB aligned if start_sector/8 = integer.

If start_sector/8 = non-integer, then the volume is 4KiB mis-aligned and automatically Windows 7 non-compliant; However, a volume like that works normal under Windows 7, its just that such an AF volume will underperform when using it as a boot partition.
======================================================================

Hi,

I tested the free edition MiniTool Partition Wizard Home Edition 7.1 (PWWin7), and MiniTool Partition Wizard Bootable CD 7.1 (PWBootCD); links: see above.

Upon shifting existing DM-created partitions, both PWWin7 and PWBootCD put the start sector of the partition (primary as well a logical ones) at a position which becomes Windows 7 non-compliant but still 4KiB aligned. In the screenshot that follows (2TBafterPWPInfo.PNG), my external 2TB AF drive (Disk 1 in DM, Disk 2 in PartitionInfo) is the disk under test by PWWin7. In PartitionInfo the start sector (17,221,680) of volume I (created by DM, shifted by PWWin7) is Windows 7 non-compliant but, however, is still 4KiB aligned. In the same screenshot, volume H (start sector = 37,511,775) has been created by PWWin7 and is clearly Windows 7 non-compliant AND 4KiB mis-aligned. Also logical volume K has been created by PWWin7 (NTFS start sector = 6,891,948), is Windows 7 non-compliant and 4KiB mis-aligned. Note that the EPBR of volume K is located at sector 6,891,885 and that is 63 sectors ahead of its NTFS volume.

Partition Wizard: Win7 non-compliant, Advance Format drive mis-aligned-2tbafterpwpinfo.png
[2TBafterPWPInfo.PNG]

The same Windows 7 non-compliance and 4KiB mis-alignment can be seen in the next screenshot (1TBafterPWPInfo1.PNG) where PWBootCD was used on the system drive (Disk 0 in DM, Disk 1 in PartitionInfo). Note that the system drive of mine is a 512 physical sector drive; so 4KiB (mis-)alignment is not relevant here. Volume M (start sector = 1,649,891,565), created by PWBootCD, is clearly Windows 7 non-compliant (and, if this would have been an Advanced Format drive, 4KiB mis-aligned too). Also logical volume L has been created by PWBootCD and is clearly Windows 7 non-compliant (and 4KiB mis-aligned); note the 63 sector distance between its EPBR and NTFS volume.

Partition Wizard: Win7 non-compliant, Advance Format drive mis-aligned-1tbafterpwpinfo1.png
[1TBafterPWPInfo1.PNG]

So, volumes created by PWWin7 or PWBootCD are very likely to be Windows 7 non-compliant, and 4KiB mis-aligned too in case of AF drives. If DM-created volumes are shifted by PWWin7 or PWBootCD, then those volumes become Windows 7 non-compliant but remain 4KiB aligned if the cluster size of the volume is a multiple of 4KiB.

(However, in Window 7 Home Edition (SP1), AF drives and volumes can also be formatted by DM in cluster sizes of 512 bytes, 1KiB, or 2KiB; I've done the test and it works. I am not all too sure how the AF drive handles (from the hardware point of view) cluster sizes smaller than its physical sector size of 4KiB; probably it might depend on the hardware implementation in the AF drive. Are (1) the smaller-than-4KiB clusters just stockpiled first in the drive cache until the 4KiB is reached and only then transferred to the 4KiB physical sector onto the AF drive's platter(s); or are (2) the clusters one-by-one written onto the platters. Case (1) would imply only one Read-Modify-Write to the platter, while case (2) would require several times a Read-Modify-Write. I've done the test by timing the transfer of very large files (GBs in size) to my 2TB AF drive; the transfer time with a cluster size of 512 bytes was significantly larger (slower data rate) than the transfer time where the cluster size was 4KiB. So, for my 2TB AF drive, probably case (2) applies)

$Master File Table: with UltraDefrag one can easily visualize the location of the $MFT in the volume. Under Windows 7 the MFT has an offset of something like 30 to 35% of the volume. In my test with a 10GB volume, that means an offset of 3GB to 3.5GB from the beginning of the volume. No doubt that Windows 7 has its reason to put the MFT not at the beginning of the volume. However, volumes created by PW seem to have their MFT located at the very beginning of the volume; just wonder why that is? So again a Windows 7 non-compliance thing.

On the web site of PW (partitionwizard.com) I have not found any information about AF drives, 4KiB issues, Windows 7 compliance in partition layout, etc... On the contrary, PW runs on Windows 7 without any problem which leaves the user with the tacit impression that PW is Windows 7 compliant, BUT that is clearly NOT the case. I find it totally unacceptable that there is no mentioning, what so ever, on their web site about the fact that PWWin7 and PWBootCD creates volumes that are Windows 7 non-compliant and 4KiB mis-aligned. A significant number of users are ignorant about mis-alignment issues and if those people use PW on a Advanced Format system or Boot (C)drive, their system will underperform. I am not at all impressed by the business ethics (or better, the lack of it) of partitionwizard.com .

Johan




My System SpecsSystem Spec
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 Partition Wizard: Win7 non-compliant, Advance Format drive mis-aligned




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