re:
Tuesday, January 25, 2005 at 6:43 pm
Windows XP Annoyances Discussion Forum
Posted by Tong Narak
(3 messages posted)
NTFS Directory Corruption with Frequent File Creation
Article ID : 169404
Last Review : July 14, 2004
Revision : 1.0
SYMPTOMS
A directory in which files are repeatedly created and deleted eventually becomes
corrupt. Subsequent attempts to access files in the directory or to create or delete
files in the directory yield pop-up window indicating that the directory is corrupt
and instructing the user to run CHKDSK.
When CHKDSK is run, it generates output like the following (although the specific
file record segments affected will vary):
Deleting corrupt attribute record (16, "")
from file record segment 286.
Deleting corrupt attribute record (32, "")
from file record segment 286.
Deleting corrupt attribute record (48, "")
from file record segment 286.
Deleting corrupt attribute record (80, "")
from file record segment 286.
Deleting corrupt attribute record (144, $I30)
from file record segment 286.
Deleting corrupt file record segment 286.
Deleting orphan file record segment 8628.
Deleting index entry DirectoryName in index $I30 of file 244.
CHKDSK is recovering lost files.
CAUSE
Multiple attributes associated with a given file have the same attribute instance
tag value. This is only likely to happen in directories where many files are repeatedly
added and deleted in an "unbalanced" way.
RESOLUTION
To resolve this problem, you can do one of the following: • Run CHKDSK /f. By running
CHKDSK /f, all files contained in a directory that is corrupted in this way should
be recovered. CHKDSK is also capable of detecting when instance counts are exceptionally
large and will proactively renumber attribute instance values. Specifically, if an
attribute instance tag is larger than 0xF000, CHKDSK will send the following message
(file number will vary):
Adjusting instance tags to prevent rollover on file 252.
Thus, by periodically running read-only CHKDSK, it is possible to detect problem
directories before they become corrupt. If the above message is encountered while
running CHKDSK in read-only mode, you should schedule a full CHKDSK to correct the
problem.
-or-
• To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows
NT Server 4.0, Terminal Server Edition. For additional information, click the following
article number to view the article in the Microsoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack
STATUS
Microsoft has confirmed this to be a problem in Windows NT version 3.51. A supported
fix is now available, but has not been fully regression tested and should be applied
only to systems experiencing this specific problem. Unless you are severely impacted
by this specific problem, Microsoft recommends that you wait for the next Service
Pack that contains this fix. Contact Microsoft Technical Support for more information.
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server
4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0
Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack
4.
MORE INFORMATION
Attribute entries within an NTFS File Record Segment (FRS) are labeled with an "instance
tag" that must be unique for the attributes in a given FRS. The value for an attribute
instance tag is generated when an attribute is created. Thus, typical instance tag
values range from 0 to about 10 on most files.
If an attribute is deleted and recreated, it receives a new instance tag. Each time
a new instance tag is needed, NTFS increments a counter associated with the FRS in
question and uses the next previously unused value. Thus, instance tags can grow
without bound if attributes are repeatedly destroyed and recreated.
For the vast majority of files and directories, the scheme described above does not
result in any problems because, once created, FRS attributes tend not to be deleted
and recreated. There is one scenario that is known to be an exception. If many files
are repeatedly added to a directory and then deleted from the directory in such a
way that the "binary tree" that indexes the directory becomes unbalanced, the "index
root" attribute for the directory is repeatedly destroyed and re-created. Because
instance tags are only 16 bits in size, this means that instance tags can be duplicated
after a directory index has been rebalanced 65,535 times. Note that even if instance
tags are duplicated, the directory will not be considered corrupt unless, at some
point, it contained a sufficiently large enough number of files. Therefore this problem
may be difficult to reproduce except in directories containing large numbers of files.
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All messages in this thread [show all]
 |  |  | Sins of NTFS (Down For The Count: Thu, Jan 22, 2004, 8:22 pm) |
|  | re: (Tong Narak: Tue, Jan 25, 2005, 6:43 pm) |
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