Partition size wrong in Win Explorer

[Guest]

Using XP Pro, the size reported for a partition (C) in drive properties is
about 20 gig, while the correct size reported in logical disk manager is
about 45 gig. These two modules are getting their information from different
places. Logical disk manager gets info from the partition table on the disk.
Can anyone point me to a description of the data structure used by Windows
Explorer to display partition sizes?

A search of this forum didn't turn up anything, not did a Technet search,
but I might not be clever enough with the keywords.

TIA

 

[Bill Blanton]

Using XP Pro, the size reported for a partition (C) in drive properties is
about 20 gig, while the correct size reported in logical disk manager is
about 45 gig. These two modules are getting their information from different
places. Logical disk manager gets info from the partition table on the disk.
Can anyone point me to a description of the data structure used by Windows
Explorer to display partition sizes?

Best guess is the "total sector" field in the volume's boot sector. Both FAT
and NTFS volumes keep a total sector count in the boot sector. With backups
up to date you might try a fixboot.

A search of this forum didn't turn up anything, not did a Technet search,
but I might not be clever enough with the keywords.

http://www.microsoft.com/technet/pr...serv/reskit/prork/prcb_dis_stfl.mspx?mfr=true

See offset 0x20 for FAT32 and offset 0x28 for NTFS.

 

[Guest]

I tried fixboot, and also tried editing the partition boot block to set the
total sector field (which made the partition unbootable so I had to put it
back). Where else might that information be stored?

TIA

 

[Bill Blanton]

Was the value in the boot sector incorrect? What was it? AFAIK, the logical
disk manager has only two places to get the information. The boot record or
the partition table in the MBR. Storing it elsewhere as "data" would be redundant,
and could create a lot of problems.

Run a partnfo and post the output.
http://terabyteunlimited.com/utilities.html#partinfo

 

[Guest]

Run a partnfo and post the output.
http://terabyteunlimited.com/utilities.html#partinfo

BOOT SECTOR INFORMATIO
-------------------------------------------------------------------------------
File System ID: 0x7 LBA: 63 Total Sectors: 94863762 ID: 0x1
Jump: EB 52 90
OEM Name: NTFS
Bytes Per Sec: 512
Sec Per Clust: 8
Res Sectors: 0
Zero 1: 0x0
Zero 2: 0x0
NA 1: 0x0
Media: 0xF8
Zero 3: 0x0
Sec Per Track: 63
Heads: 255
Hidden Secs: 63
NA 2: 0x0
NA 3: 0x800080
Total Sectors: 0x0253EA7F
MFT LCN: 0x0C0000
MFT Mirr LCN: 0x0253EA7
Clust Per FRS: 0xF6
Clust Per IBlock: 0x1
Volume SN: 0xCA706C98706C8CCF
Checksum: 0x0
Boot Flag: 0xAA55

As you can see, total sectors is different in the two places. Very strange.
Changing total sectors in the boot record to match the partition table makes
the partition unbootable -- also strange.

Joe

 

[Bill Blanton]

BOOT SECTOR INFORMATION

OEM Name: NTFS
Bytes Per Sec: 512
Sec Per Clust: 8
Res Sectors: 0
Sec Per Track: 63
Heads: 255
Hidden Secs: 63
Total Sectors: 0x0253EA7F
MFT LCN: 0x0C0000

As you can see, total sectors is different in the two places. Very strange.
Changing total sectors in the boot record to match the partition table makes
the partition unbootable -- also strange.

Those numbers do match what you saw in your original post.. You
might have better luck changing the PT to match the boot sector and then
either partitioning the remaining unallocated space as a separate volume,
or extending the partition.

The total sectors in the partition table should be (boot sector total +1), as NTFS
uses that last sector for a hidden boot sector backup.


0x0253EA80 (decimal 39053952)

I usually use ptedit (Powerquest/Symantec)
ftp://ftp.symantec.com/public/english_us_canada/tools/pq/utilities/