Sprite 1984

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Text File | 1990-03-19 | 17.8 KB | 465 lines

FSCHECK User Commands FSCHECK _________________________________________________________________ NNAAMMEE fscheck - perform consistency check on file system SSYYNNOOPPSSIISS ffsscchheecckk --ddeevv _d_e_v_i_c_e --ppaarrtt _p_a_r_t_i_t_i_o_n [[_o_p_t_i_o_n_s] OOPPTTIIOONNSS --ddeevv _d_e_v_i_c_e _D_e_v_i_c_e is the root name of a device, i.e. rxy0, rsd1, rsb0 --ppaarrtt _p_a_r_t_i_t_i_o_n _P_a_r_t_i_t_i_o_n is a letter indicating a partition, i.e. a, b, c, d, e, f, g. --ddiirr _d_e_v_D_i_r _D_e_v_D_i_r is an alternate directory in which to find the device file named by concatenating _D_e_v_i_c_e and _P_a_r_t_i_t_i_o_n. The default directory name is ``/dev/``. --iinniittiiaallPPaarrtt _f_i_r_s_t_P_a_r_t_N_a_m_e _f_i_r_s_t_P_a_r_t_N_a_m_e is the name of the initial par- tition on the disk which contains basic disk geometry information. The default is parti- tion ``a''. --wwrriittee Write the disk when errors are encountered and fixed. The default is to not write the disk. --ssiilleenntt Don't say anything unless there is an error. --vveerrbboossee Output verbose information about errors. The default is to print out terse information. --iinnccVVeerrssiioonn If the domain was not written back properly on system shutdown then all version numbers will be incremented. --ffiixxRRoooott Re-create a missing or corrupted root direc- tory. --cclleeaarr Clear the domain number field stored in the summary sector. --hhoossttIIDD _i_d Update the host ID in the disk header. If _i_d is not 0 then it is used as the host id to put in the header. If _i_d equals 0 then one of two values are used as the host id. If the device server is the local host then the kernel's internal idea of its host id is used, other- wise the device server's id is used. Sprite v.1.0 Printed: March 19, 1990 1 FSCHECK User Commands FSCHECK --bbaaddBBlloocckk Initialize the bad block file descriptor. --oouuttppuuttFFiillee _o_u_t_p_u_t_F_i_l_e All output to stdout and stderr is also appended to _o_u_t_p_u_t_F_i_l_e. --bbuuffffeerrSSiizzee _s_i_z_e Set the size of the buffer associated with _o_u_t_p_u_t_F_i_l_e to _s_i_z_e bytes. Default is to use whatever buffer is provided by the stdio library. This option has no effect if the --oouuttppuuttFFiillee option is not used. --rroooottPPaarrtt This option controls the output to a file. If the --oouuttppuuttFFiillee option is not given then this option has no effect. Otherwise, the output is stored in a buffer and only written to the file when the program exits. This allows the output to be written to a file on the parti- tion being checked (usually the output is written to the root partition). The file IO in this case is very primative and restric- tive. The output file must be in the root directory and must exist prior to running ffsscchheecckk. If the size of the output exceeds the size of the file or if it exceeds the size of the direct data blocks then it will be truncated. If the output exceeds the size of the internal buffer it will be truncated (see --bbuuffffeerrSSiizzee ). If the output is smaller than the size of the file, the remaining part of the file will be filled with null characters. Any file produced by this option will have a decimal number in the first line which represents the number of bytes in the file. This is used by ffsscchheecckk to calculate the starting point for appending. The output file can be reset by either setting the first number to 0 or by overwriting the file with null characters. --hheeaappLLiimmiitt _s_i_z_e Program will not allocate more than _s_i_z_e bytes of memory. Default is to allocate as much as is needed. --ddeelleettee If a data block is shared by more than one file, delete it from all but one of the files. The default is to make a copy of the block for each file sharing the original. --rreeaaddBBlloocckk _c_o_u_n_t Sprite v.1.0 Printed: March 19, 1990 2 FSCHECK User Commands FSCHECK Read count blocks at a time when reading the file descriptors. Currently this does not pro- vide better performance due to limitations in the disk interface library. --ddeebbuugg Print out debugging information. --bbiittmmaappVVeerrbboossee Print out lots and lots of information about errors in the bitmaps. --nnuummRReebboooott _c_o_u_n_t Number of consecutive times to reboot before returning a warning indication. --cclleeaarrFFiixxCCoouunntt Clear consecutive fix counter. _________________________________________________________________ DDEESSCCRRIIPPTTIIOONN This program will perform a consistency check on a file sys- tem. By default it will report inconsistencies but won't repair them. If the --wwrriittee option is used then it will repair any inconsistencies by modifying the disk as neces- sary. This program performs the following consistency checks: 1. It makes sure that the file descriptor allocation bit map agrees with the status information kept in each file descriptor. If necessary it will correct the bit map. 2. It confirms that data-block and indirect-block pointers are valid. If a pointer is invalid then the pointer is set to NIL and the file size is adjusted as necessary to reflect the new size of the file. 3. It recreates the data block allocation bit map based on information in the file descriptors and indirect blocks. 4. It checks for blocks that are allocated to more than one file. If a block is multiply allocated then copies of the block are made and all but one of the files is corrected to use a copy. If the --ddeelleettee option is given, or if only a subset of the fragments in a block are shared, then the block is given to the lowest num- bered file descriptor and it is removed from all other files that reference it. A special case is made of block 0. This block belongs to the root directory and is copied (or deleted) for all other files even if the Sprite v.1.0 Printed: March 19, 1990 3 FSCHECK User Commands FSCHECK root directory is corrupted or doesn't exist. 5. It verifies that directories are of the proper format. In order to patch a directory, names may be deleted, the directory may be truncated, or in the worst case the directory may be turned into a normal file. 6. It puts unreferenced files into the lost+found direc- tory. The name of each file in the lost+found direc- tory is the file's file descriptor number. 7. It corrects link counts and block counts in each file descriptor. 8. It checks that indirect blocks contain valid pointers. If the pointers are invalid and the block is part of a file then a hole is created, otherwise if the block is part of a directory then the directory is truncated. 9. It checks that each file descriptor contains a valid magic number. If this is not the case then the file descriptor is cleared and marked as unused in the bit- map. 10. It recreates the root directory if it is corrupted and the --ffiixxRRoooott option is given. By default only terse information is given about the errors in the file system. Only the first error per file is reported. If the --vveerrbboossee option is given then more verbose information will be given. If the --bbiittmmaappVVeerrbboossee option is given then differences between the bitmaps on disk and the recreated bitmaps are printed. Since the bitmaps on disk are not kept current use of this option is likely to produce lots of output. The ffsscchheecckk program will also perform other actions depend- ing on the options that are specified. If the --iinnccVVeerrssiioonn option is given then flags in the file system header are checked to see if the file system was safely written back when it was detached or the system went down. If it is determined that the file system was not safely written back then the version numbers for all files in the file system are incremented. This will cause all reopens of files because of recovery to fail. If the --ffiixxRRoooott option is given the root directory will be recreated if it has become corrupted. If the root is recreated, then any directories that have the root directory as their parent will be inserted into the root with their file descriptor number as their name. Any files that used to be in the root directory will be placed in lost+found. Sprite v.1.0 Printed: March 19, 1990 4 FSCHECK User Commands FSCHECK FFsscchheecckk assumes that data block 0 belongs to the root direc- tory and will allocate this block to the directory when reconstructing it. The --ffiixxRRoooott option requires reading the root directory twice, hence it cannot be used without the --wwrriittee option. The --cclleeaarr option should be used if the domain number field should be cleared from the summary sector. Each file system that is attached is given a domain number under which it can be identified. When a file system is attached, the system will try to attach it with the same domain number that it was attached under last time. This is required to allow clients of the file system to recover when the file system is reattached. If the domain number field is cleared from the summary sector, then the system will attach the file system under a domain number of the system's choosing. The --hhoossttIIDD option will force the system to update the host id in the file system header. If the device under which the file system is being attached is generic then the id of the host on which ffsscchheecckk is run is used. Otherwise the host id specified by the device file is used. The default is not to modify the host id. The --bbaaddBBlloocckk option will initialize the file descriptor which points to bad disk blocks. Initializing it will clear out any pointers to bad blocks that are currently in the file descriptor. The --hheeaappLLiimmiitt option can be used to place an upper limit on the size of the program heap. This can be used to prevent paging, since paging cannot be done at the point in the boot sequence when ffsscchheecckk is run. If ffsscchheecckk cannot complete checking the disk because of the limit then it will do as much as it can. This should allow multiple runs of ffsscchheecckk to completely check the disk. The limit is only an approxi- mation of how large ffsscchheecckk will grow, since the program stack is not restricted. Therefore the limit should be set as high as possible but it should not be set to the boundary at which paging will occur. If it is set too small then ffsscchheecckk may not be able to run at all. Note that the bbuuffffeerr-- SSiizzee and rreeaaddBBlloocckk options will affect the amount of heap required. As a rule of thumb, the amount of heap space needed by ffsscchheecckk is proportional to the disk size and the amount of errors on the disk. A heap limit of 1 Mb should be sufficient for all but the most extreme cases. Each time ffsscchheecckk runs and finds an error in a partition, a counter on disk is incremented. The value of this counter is the number of consecutive times ffsscchheecckk has run on the par- tition and corrected an error. If the counter exceeds the value given by the --nnuummRReebboooott option (default 4) and if Sprite v.1.0 Printed: March 19, 1990 5 FSCHECK User Commands FSCHECK ffsscchheecckk corrects an error, then ffsscchheecckk will return EXIT_NOREBOOT instead of the standard soft error indication. This allows higher level software to avoid infinite reboot loops. The --cclleeaarrFFiixxCCoouunntt option resets the consecutive counter to 0. Finally, the --oouuttppuutt, --bbuuffffeerrSSiizzee and --nnooFFlluusshh options con- trol the output from fscheck. The --oouuttppuutt option allows the output from fscheck to be put into a file as well as printed on stdout and stderr. The --bbuuffffeerrSSiizzee option sets the size of the IO buffer associated with the output file. The --nnooFFlluusshh option prevents the buffer from being flushed until the disk has been checked and corrected. This allows the output to be written to the disk being checked. If the out- put exceeds the size of the buffer then it is truncated to the buffer size. If the buffer size is exceeded in the mid- dle of an output string, then remainder of the string will wrap over the beginning of the buffer. EEXXIITT CCOODDEESS FFsscchheecckk has a large number of exit codes. Positive values indicate that some sort of error occurred that requires ffsscchheecckk be run again, although an exit code of 1 indicates that the filesystem was corrupted but was successfully corrected. Negative error codes indicate that a serious error occurred that requires user action before fscheck can be run again. 0 No errors occurred and no errors were fixed in the filesystem. 1 Errors were fixed in the filesystem. 2 FFsscchheecckk ran out of memory before it was able to com- pletely check the disk. Rerunning with the same heap limit should allow ffsscchheecckk to finish. 3 Errors were fixed in the filesystem and the number of consecutive times ffsscchheecckk has fixed this partition exceeds the limit. -1 An unspecified hard error occurred. -2 A disk read failed. -3 A disk write failed. -4 There was a problem with one of the arguments. -5 The heap limit is too small for ffsscchheecckk to run. The Sprite v.1.0 Printed: March 19, 1990 6 FSCHECK User Commands FSCHECK heap limit must be made larger before rerunning ffsscchheecckk. -6 The disk is full so that duplicate blocks cannot be copied. Either delete some stuff or rerun using the --ddeelleettee option. BBUUGGSS//FFEEAATTUURREESS Indirect blocks are always marked as in use in the bitmap, even if they contain invalid entries. This is because the block may be in use by another file and cannot be marked as free. The --ffiixxRRoooott option cannot be used without the --wwrriittee option. KKEEYYWWOORRDDSS file system, disk Sprite v.1.0 Printed: March 19, 1990 7