![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to check.8 CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Research Unix] / researchv10dc / dist / man / v4 / man8|
Return to check.8 CVS log | Up to [Research Unix] / researchv10dc / dist / man / v4 / man8 |
1.1 root 1: .th CHECK VIII 8/31/73
2: .sh NAME
3: check \*- file system consistency check
4: .sh SYNOPSIS
5: .bd check
6: [
7: .bd \*-lsib
8: [ numbers ]
9: ]
10: [ filesystem ]
11: .sh DESCRIPTION
12: .it Check
13: examines a file system,
14: builds a bit map of used blocks,
15: and compares this bit map against
16: the free list maintained on the file system.
17: It also reads directories and compares
18: the link-count in each i-node with the number of directory
19: entries by which it is referenced.
20: If the file system is not specified,
21: a check of a
22: default file system
23: is performed.
24: The normal output of
25: .it check
26: includes a report of
27: .s3
28: .lp +4 0
29: The number of blocks missing; i.e. not in any file
30: nor in the free list,
31: .lp +4 0
32: The number of special files,
33: .lp +4 0
34: The total number of files,
35: .lp +4 0
36: The number of large files,
37: .lp +4 0
38: The number of directories,
39: .lp +4 0
40: The number of indirect blocks,
41: .lp +4 0
42: The number of blocks used in files,
43: .lp +4 0
44: The highest-numbered block appearing in a file,
45: .lp +4 0
46: The number of free blocks.
47: .s3
48: .i0
49: The
50: .bd \*-l
51: flag causes
52: .it check
53: to produce as part of its output report a list of the
54: all the path names of files on the file system.
55: The list is in i-number order; the first
56: name for each file gives the i-number while subsequent
57: names (i.e. links) have the i-number suppressed.
58: The entries ``\fB.\fR'' and ``\fB..\fR''
59: for directories are also suppressed.
60: .s3
61: The
62: .bd \*-s
63: flag causes
64: .it check
65: to ignore the actual free list and reconstruct a new one
66: by rewriting the super-block of the file system.
67: The file system should be dismounted while this is done;
68: if this is not possible (for example if
69: the root file system has to be salvaged)
70: care should be taken that the system is quiescent and that
71: it is rebooted immediately afterwards so that the old, bad in-core
72: copy of the super-block will not continue to be used.
73: Notice also that
74: the words in the super-block
75: which indicate the size of the free list and of the
76: i-list are believed.
77: If the super-block has been curdled
78: these words will have to be patched.
79: The
80: .bd \*-s
81: flag
82: causes the normal output reports to be suppressed.
83: .s3
84: The occurrence
85: of
86: .bd i
87: .it n
88: times in a flag argument
89: .bd \*-ii...i
90: causes
91: .it check
92: to store away the next
93: .it n
94: arguments which are taken to be i-numbers.
95: When any of these i-numbers is encountered in a directory
96: a diagnostic is produced, as described below, which indicates among
97: other things the entry name.
98: .s3
99: Likewise,
100: .it n
101: appearances of
102: .bd b
103: in a flag like
104: .bd \*-bb...b
105: cause the next
106: .it n
107: arguments to be taken as block numbers
108: which are remembered;
109: whenever any of the named blocks turns up in a file,
110: a diagnostic is produced.
111: .sh FILES
112: Currently, /dev/rp0 is the default file system.
113: .sh "SEE ALSO"
114: fs (V)
115: .sh DIAGNOSTICS
116: There are some self-evident diagnostics like
117: ``can't open ...'', ``can't write ....''
118: If a read error is encountered,
119: the block number of the bad block is printed and
120: .it check
121: exits.
122: ``Bad freeblock'' means that
123: a block number outside the available space was encountered in the free list.
124: ``\fIn\fR dups in free''
125: means that \fIn\fR blocks were found in the free list which
126: duplicate blocks either in some file or in the earlier part of the free list.
127: .s3
128: An important class of diagnostics is produced by a routine which
129: is called for each block which is encountered in an i-node
130: corresponding to an ordinary file or directory.
131: These have the form
132: .s3
133: .dt
134: \fIb# complaint \fB; i= \fIi# \fB(\fIclass \fB)\fR
135: .s3
136: Here
137: .it b#
138: is the block number being considered;
139: .it complaint
140: is the diagnostic itself.
141: It may be
142: .s3
143: .lp +8 5
144: \fBblk\fR if the block number was mentioned as an argument
145: after
146: .bd \*-b;
147: .lp +8 5
148: \fBbad\fR if the block number has a value not inside the allocatable space
149: on the device, as indicated by the devices's super-block;
150: .lp +8 5
151: \fBdup\fR if the block number has already been seen in a file;
152: .lp +8 5
153: \fBdin\fR if
154: the block is a member of a directory, and if an entry is found
155: therein whose i-number is outside the
156: range of the i-list on the device, as indicated by the
157: i-list size specified by the super-block.
158: Unfortunately this diagnostic does not indicate the
159: offending entry name, but since the i-number
160: of the directory itself is given (see below)
161: the problem can be tracked down.
162: .s3
163: .i0
164: The
165: .it i#
166: in the form above is the i-number in which the named block was found.
167: The
168: .it class
169: is an indicator of what type of block was involved in the
170: difficulty:
171: .s3
172: .lp +8 5
173: \fBsdir\fR indicates that the block is a data block in a small file;
174: .lp +8 5
175: \fBldir\fR indicates that the block is a data block in a large file
176: (the indirect block number is not available);
177: .lp +8 5
178: \fBidir\fR indicates that the block is an indirect block
179: (pointing to data blocks) in a large file;
180: .lp +8 5
181: \fBfree\fR indicates that the block was mentioned after
182: .bd \*-b
183: and is free;
184: .lp +8 5
185: \fBurk\fR indicates a malfunction in
186: .it check.
187: .s3
188: .i0
189: When an i-number specified after
190: .bd \*-i
191: is encountered while reading a directory,
192: a report in the form
193: .s3
194: \fi# \fBino; i= \fId# \fB(\fIclass \fB) \fIname\fR
195: .s3
196: where
197: .it i#
198: is the requested i-number.
199: .it d#
200: is the i-number of the directory,
201: .it class
202: is the class of the directory block as discussed above
203: (virtually always
204: ``sdir'')
205: and
206: .it name
207: is the entry name.
208: This diagnostic gives enough information
209: to find a full path name for an i-number
210: without using the
211: .bd -l
212: option:
213: use
214: .bd \*-b
215: .it n
216: to find an entry name and
217: the i-number of the directory containing the reference to
218: .it n,
219: then recursively use
220: .bd \*-b
221: on the i-number of the directory to find its name.
222: .s3
223: Another important class of
224: file system diseases indicated
225: by
226: .it check
227: is files for which the number of directory entries does
228: not agree with the link-count field of the i-node.
229: The diagnostic is hard to interpret.
230: It has the form
231: .s3
232: .dt
233: .ft I
234: i# delta
235: .ft R
236: .s3
237: Here
238: .it i#
239: is the i-number affected.
240: .it Delta
241: is an octal number accumulated in a byte, and thus can have the
242: value 0 through 377(8).
243: The easiest way (short of rewriting the routine)
244: of explaining the significance of
245: .it delta
246: is to describe how it is computed.
247: .s3
248: If the associated i-node is allocated
249: (that is, has the
250: .it allocated
251: bit on)
252: add 100 to
253: .it delta.
254: If its link-count is non-zero,
255: add another 100 plus the link-count.
256: Each time a directory entry specifying
257: the associated i-number is encountered,
258: subtract 1 from
259: .it delta.
260: At the end,
261: the i-number and
262: .it delta
263: are printed if
264: .it delta
265: is neither 0 nor 200.
266: The first case indicates that the i-node was unallocated
267: and no entries for it appear;
268: the second that it was allocated
269: and that the link-count and the number of directory entries agree.
270: .s3
271: Therefore (to explain the symptoms of the most common difficulties)
272: .it delta
273: = 377 (\*-1 in 8-bit, 2's complement octal)
274: means that there is a directory entry for an unallocated
275: i-node.
276: This is somewhat serious and the entry should be be found and removed forthwith.
277: .it Delta
278: = 201 usually means that a normal,
279: allocated i-node has no directory entry.
280: This difficulty is much less serious.
281: Whatever blocks there are in the file
282: are unavailable, but no further damage
283: will occur if nothing is done.
284: A
285: .it clri
286: followed by a
287: .it "check \*-s"
288: will restore the lost space at leisure.
289: .s3
290: In general,
291: values of
292: .it delta
293: equal to or somewhat above 0, 100, or 200
294: are relatively innocuous;
295: just below these numbers there is danger of
296: spreading infection.
297: .sh BUGS
298: Unfortunately,
299: .it "check \*-l"
300: on file systems
301: with more than 3000 or so files
302: does not work because it runs out of core.
303: .s3
304: Since
305: .it check
306: is inherently two-pass in nature, extraneous diagnostics
307: may be produced if applied to active file systems.
308: .s3
309: It believes even preposterous super-blocks and
310: consequently can get core images.
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.