diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/nfs/pnfs-scsi-server.txt | 23 | ||||
| -rw-r--r-- | Documentation/filesystems/ocfs2-online-filecheck.txt | 94 | ||||
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 7 |
3 files changed, 121 insertions, 3 deletions
diff --git a/Documentation/filesystems/nfs/pnfs-scsi-server.txt b/Documentation/filesystems/nfs/pnfs-scsi-server.txt new file mode 100644 index 000000000000..5bef7268bd9f --- /dev/null +++ b/Documentation/filesystems/nfs/pnfs-scsi-server.txt @@ -0,0 +1,23 @@ + +pNFS SCSI layout server user guide +================================== + +This document describes support for pNFS SCSI layouts in the Linux NFS server. +With pNFS SCSI layouts, the NFS server acts as Metadata Server (MDS) for pNFS, +which in addition to handling all the metadata access to the NFS export, +also hands out layouts to the clients so that they can directly access the +underlying SCSI LUNs that are shared with the client. + +To use pNFS SCSI layouts with with the Linux NFS server, the exported file +system needs to support the pNFS SCSI layouts (currently just XFS), and the +file system must sit on a SCSI LUN that is accessible to the clients in +addition to the MDS. As of now the file system needs to sit directly on the +exported LUN, striping or concatenation of LUNs on the MDS and clients +is not supported yet. + +On a server built with CONFIG_NFSD_SCSI, the pNFS SCSI volume support is +automatically enabled if the file system is exported using the "pnfs" +option and the underlying SCSI device support persistent reservations. +On the client make sure the kernel has the CONFIG_PNFS_BLOCK option +enabled, and the file system is mounted using the NFSv4.1 protocol +version (mount -o vers=4.1). diff --git a/Documentation/filesystems/ocfs2-online-filecheck.txt b/Documentation/filesystems/ocfs2-online-filecheck.txt new file mode 100644 index 000000000000..1ab07860430d --- /dev/null +++ b/Documentation/filesystems/ocfs2-online-filecheck.txt @@ -0,0 +1,94 @@ + OCFS2 online file check + ----------------------- + +This document will describe OCFS2 online file check feature. + +Introduction +============ +OCFS2 is often used in high-availaibility 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 furhter 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 volumn 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 +defalut 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 receivng 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. diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index 223c32171dcc..cf51360e3a9f 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -56,9 +56,10 @@ iocharset=<name> -- Character set to use for converting between the you should consider the following option instead. utf8=<bool> -- UTF-8 is the filesystem safe version of Unicode that - is used by the console. It can be enabled for the - filesystem with this option. If 'uni_xlate' gets set, - UTF-8 gets disabled. + is used by the console. It can be enabled or disabled + for the filesystem with this option. + If 'uni_xlate' gets set, UTF-8 gets disabled. + By default, FAT_DEFAULT_UTF8 setting is used. uni_xlate=<bool> -- Translate unhandled Unicode characters to special escaped sequences. This would let you backup and |
