Just to add to this - the same results happen when using non-mmap
reads/writes (-R & -W to fsx). Results:
READ BAD DATA: offset = 0x2f5dc, size = 0xa930
OFFSET  GOOD    BAD     RANGE
0x2f5dc 0x0000  0xd76c  0x   78
....
493(237 mod 256): READ  0x68f2 thru 0x11c70     (0xb37f bytes)
494(238 mod 256): WRITE 0x7c8e thru 0x1604a     (0xe3bd bytes)
495(239 mod 256): READ  0x14eca thru 0x1ea7a    (0x9bb1 bytes)
496(240 mod 256): READ  0x84eb thru 0x156c4     (0xd1da bytes)
497(241 mod 256): TRUNCATE DOWN from 0x1ea7b to 0x5120
498(242 mod 256): READ  0x35b8 thru 0x511f      (0x1b68 bytes)
499(243 mod 256): WRITE 0x388ee thru 0x3ffff    (0x7712 bytes) HOLE
***WWWW
500(244 mod 256): READ  0x2f5dc thru 0x39f0b    (0xa930 bytes)  ***RRRR***

So it did a read @0x2f5dc, which should have been a hole in the file
(after the truncate down to 0x5120), but it got back non-zero data.

Andre

Andre Renaud wrote:
<snip>
> I've attached the truncated output of fsx, although the relevant parts
> are the top:
> READ BAD DATA: offset = 0xdd7c, size = 0xd933
> OFFSET  GOOD    BAD     RANGE
> 0x f000 0x0000  0x6c22  0x  7fc
> 
> and the bottom:
> 9602(130 mod 256): MAPREAD      0x2d86c thru 0x382f1    (0xaa86 bytes)
> 9603(131 mod 256): TRUNCATE DOWN        from 0x3c5fd to 0xb013  ******WWWW
> 9604(132 mod 256): WRITE        0x19606 thru 0x282e0    (0xecdb bytes)
> HOLE     ***WWWW
> 9605(133 mod 256): WRITE        0x1d4e2 thru 0x1dfd5    (0xaf4 bytes)
> 9606(134 mod 256): MAPREAD      0xdd7c thru 0x1b6ae     (0xd933 bytes)
> ***RRRR***
> 
> This indicates that at offset 0xf000, it was expecting to read nuls
> (GOOD: 0x0000), but it read non null (BAD: 0x6c22), having done a
> truncate down to 0xb013,
> 
> Does anyone know about anything like this?
> Andre


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       Andre Renaud                             Bluewater Systems Ltd
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