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DISK FILE DAMAGE ASSESSMENT PROGRAM
This document reflects the software of version
The information in this document is subject to
change without notice and should not be
construed as a commitment by Digital Equipment
Actual distribution of the software described
in this specification will be subject to terms
and conditions to be announced at some future
date by Digital Equipement Corporation.
DEC assumes no responsibility for the use or
reliability of its software on equipment which
is not supplied by DEC.
This software is furnished to purchaser under a
license to use on a single computer system and
can be copied (with inclusion of DEC's
copyright notice) only for use in such system,
except as may otherwise be provided in writing
DSKRAT Page 2
DSKRAT is a damage assessment program for Level D disk file
structures. It scans the file structure, using super
USETI's to read files, and reports any inconsistencies
detected to device LPT. File name RAT.LST is used if LPT is
a directory device.
2.0 DSKRAT OPERATIONS
To run DSKRAT, log in as [1,2] (required for super USETI),
assign to a file structure the logical name STR, assign LPT
if you wish it to be some device other than the printer, and
run DSKRAT. DSKRAT opens STR and LPT, reads the SAT blocks
into core and, if everything is acceptable, types RUNNING,
and begins to scan the file structure.
Note that DSKRAT now has a Lost Block Recovery routine which
will get called if the following additional conditions are
met. 1) You must be the only job logged in and 2)
Scheduling must be set for no more logins.
If these conditions are not met, DSKRAT types "%Lost Block
Recovery Will Not Be Done" followed by the reasons for the
failure, and processing will continue as with earlier
If the Lost Block Recovery routine is called and Lost Blocks
are encountered in its normal scan operations then files
with the name LSTBLK.XXX, where XXX is an incremental
extension beginning with '001', will be created. The RIBS
for these files will be modified, via Super-USETO's, to
point to all Lost Blocks found on the specified unit(s).
DSKRAT looks up each file on the file structure and reports
any failures, reads and verifies all RIBs of the file,
checksums each group and reports errors, reads the retrieval
information from the RIBs and constructs its own SAT blocks.
If there are any disagreements between the SAT's read from
disk and SAT's constructed by DSKRAT, error messages are
output. That is, if any cluster is in more than one file,
or in a file but not marked in the SAT, that fact is
reported and the cluster and the file to which it belongs
are identified. One line is produced for each error. It
includes the file name, cluster number and logical block
number of the cluster in question, and an error comment.
When DSKRAT has gone through the file structure completely,
it prints a list of clusters in more than one file, clusters
DSKRAT Page 3
in files by not marked in SAT's, and clusters marked in
SAT's but not in any file. Then, if any clusters are in
more than one file, it types
END OF PASS 1, BEGINNING PASS 2
and starts over. The second pass will produce an error line
for every file claiming clusters used by more than one file.
The first such file is not known in pass 1 until the second
is found. If pass 2 is not wanted, type CONTROL-C twice and
REENTER. This will close LPT and DSKRAT will exit.
If no clusters are in more than one file, DSKRAT types
END OF PASS 1, NO NEED FOR PASS 2
Note that since DSKRAT reads in SAT's at the beginning of
the program, if other users are referencing the disks
(writing or deleting files or reading files marked for
deletion) the SAT blocks will not be current and spurious
errors will appear. However, true errors will not be
3.0 FLOW FOR DSKRAT
Read and verify home blocks, print if
errors are found.
Print the file structure name, blocks
per cluster, time, and date.
Initialize disk SAT (find SAT.SYS RIB
from the home block and read the SAT
Clear the computed SAT and the trouble
Read and verify MFD RIB, print if errors
3.1 PASS1: Call DOMFD.
DSKRAT Page 4
3.2 END PASS 1: List all lost clusters. (For each
cluster, list if the non-computed-SAT
and the disk-SAT = 1).
List all free clusters. (For each
cluster, list if the computed-SAT and
the non-disk-SAT = 1).
List all clusters used for more than one
file. (For each cluster, list if the
trouble-SAT = 1).
Type END OF PASS 1
If there are no clusters used for more
than one file, type
NO NEED FOR PASS 2
Otherwise, type BEGINNING PASS 2
3.3 PASS 2: Clear the computed SAT.
3.4 DOMFD: For all files in the MDF,
If the extension is UFD,
Get the CFP (which points to the
Read and verify the first UFD RIB.
If the RIB is acceptable,
For all files in the UFD,
Perform an extended lookup
(through FILSER), print if it
Get the CFP (which points to the
Read and verify the first RIB and
all extended RIBs, print if an
If any clusters are non-existent,
print and don't check the SAT's.
DSKRAT Page 5
Checksum each group (unless
RIPABC=1), print if an error
Mark the clusters allocated to
this file in the computed SAT.
If any clusters are already
allocated or have a bit set in
the trouble SAT (for pass 2),
Set the bits in the trouble
If any clusters are not allocated
in the disk SAT, print FREE.