diff options
Diffstat (limited to 'Documentation/filesystems/ocfs2-online-filecheck.txt')
| -rw-r--r-- | Documentation/filesystems/ocfs2-online-filecheck.txt | 94 |
1 files changed, 0 insertions, 94 deletions
diff --git a/Documentation/filesystems/ocfs2-online-filecheck.txt b/Documentation/filesystems/ocfs2-online-filecheck.txt deleted file mode 100644 index 139fab175c8a..000000000000 --- a/Documentation/filesystems/ocfs2-online-filecheck.txt +++ /dev/null @@ -1,94 +0,0 @@ - OCFS2 online file check - ----------------------- - -This document will describe OCFS2 online file check feature. - -Introduction -============ -OCFS2 is often used in high-availability systems. However, OCFS2 usually -converts the filesystem to read-only when encounters an error. This may not be -necessary, since turning the filesystem read-only would affect other running -processes as well, decreasing availability. -Then, a mount option (errors=continue) is introduced, which would return the --EIO errno to the calling process and terminate further processing so that the -filesystem is not corrupted further. The filesystem is not converted to -read-only, and the problematic file's inode number is reported in the kernel -log. The user can try to check/fix this file via online filecheck feature. - -Scope -===== -This effort is to check/fix small issues which may hinder day-to-day operations -of a cluster filesystem by turning the filesystem read-only. The scope of -checking/fixing is at the file level, initially for regular files and eventually -to all files (including system files) of the filesystem. - -In case of directory to file links is incorrect, the directory inode is -reported as erroneous. - -This feature is not suited for extravagant checks which involve dependency of -other components of the filesystem, such as but not limited to, checking if the -bits for file blocks in the allocation has been set. In case of such an error, -the offline fsck should/would be recommended. - -Finally, such an operation/feature should not be automated lest the filesystem -may end up with more damage than before the repair attempt. So, this has to -be performed using user interaction and consent. - -User interface -============== -When there are errors in the OCFS2 filesystem, they are usually accompanied -by the inode number which caused the error. This inode number would be the -input to check/fix the file. - -There is a sysfs directory for each OCFS2 file system mounting: - - /sys/fs/ocfs2/<devname>/filecheck - -Here, <devname> indicates the name of OCFS2 volume device which has been already -mounted. The file above would accept inode numbers. This could be used to -communicate with kernel space, tell which file(inode number) will be checked or -fixed. Currently, three operations are supported, which includes checking -inode, fixing inode and setting the size of result record history. - -1. If you want to know what error exactly happened to <inode> before fixing, do - - # echo "<inode>" > /sys/fs/ocfs2/<devname>/filecheck/check - # cat /sys/fs/ocfs2/<devname>/filecheck/check - -The output is like this: - INO DONE ERROR -39502 1 GENERATION - -<INO> lists the inode numbers. -<DONE> indicates whether the operation has been finished. -<ERROR> says what kind of errors was found. For the detailed error numbers, -please refer to the file linux/fs/ocfs2/filecheck.h. - -2. If you determine to fix this inode, do - - # echo "<inode>" > /sys/fs/ocfs2/<devname>/filecheck/fix - # cat /sys/fs/ocfs2/<devname>/filecheck/fix - -The output is like this: - INO DONE ERROR -39502 1 SUCCESS - -This time, the <ERROR> column indicates whether this fix is successful or not. - -3. The record cache is used to store the history of check/fix results. It's -default size is 10, and can be adjust between the range of 10 ~ 100. You can -adjust the size like this: - - # echo "<size>" > /sys/fs/ocfs2/<devname>/filecheck/set - -Fixing stuff -============ -On receiving the inode, the filesystem would read the inode and the -file metadata. In case of errors, the filesystem would fix the errors -and report the problems it fixed in the kernel log. As a precautionary measure, -the inode must first be checked for errors before performing a final fix. - -The inode and the result history will be maintained temporarily in a -small linked list buffer which would contain the last (N) inodes -fixed/checked, the detailed errors which were fixed/checked are printed in the -kernel log. |