X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=Documentation%2Flfsck.txt;h=2b42d19a36d34ad9881626929f417daeed61d4f9;hp=246fcb158d1eaf5e8f57761fd010436f7ffa0954;hb=204b492ce0856cc03c6e8bf88e925c8c18bc3304;hpb=5ebc00ec79565ad62e978af65b023343ad360675 diff --git a/Documentation/lfsck.txt b/Documentation/lfsck.txt index 246fcb1..2b42d19 100644 --- a/Documentation/lfsck.txt +++ b/Documentation/lfsck.txt @@ -163,9 +163,12 @@ osd-ldiskfs.-.full_scrub_threshold_rate). On starting, the master engine sends RPCs to other MDTs (when necessary) to start other master engines and to related OSTs to start the slave engines. -2. The master engine on the MDT scans the MDT local device. Each object is -checked for the consistency criteria enumerated in the 'features' section of -this document. +2. The master engine on the MDS scans the MDT device using namespace iteration +(described below). For each striped file, it calls the registered LFSCK process +handlers to perform the relevant system consistency checks/repairs, which are +enumerated in the 'features' section. All objects on OSTs that are never +referenced during this scan (because, for example, they are orphans) are +recorded in an OST orphan object index on each OST. 3. After the MDT completes first-stage system scanning, the master engine sends RPCs to related LFSCK engines on other targets to notify that the first-stage @@ -194,10 +197,10 @@ Orphan objects will either be relinked to an existing file if found - or moved into a new file in .lustre/lost+found. If multiple MDTs are present, MDTs will check/repair MDT-OST consistency in -parallel. To avoid scans of the OST device the slave engine will not begin -second-stage system scans until all the master engines complete the first-stage -system scan. For each OST there is a single OST orphan object index, regardless -of how many MDTs are in the MDT-OST consistency check/repair. +parallel. To avoid redundant scans of the OST device the slave engine will not +begin second-stage system scans until all the master engines complete the +first-stage system scan. For each OST there is a single OST orphan object +index, regardless of how many MDTs are in the MDT-OST consistency check/repair. Object traversal design reference @@ -263,21 +266,21 @@ useful links: http://insidehpc.com/2013/05/02/video-lfsck-online-lustre-fil Glossary of terms =============================================== -OSD - Object storage device. A generic term for a storage device with an - interface that extends beyond a block-oriented device interface. - FID - File IDentifier. A Lustre file system identifies every file and object with a unique 128-bit ID. -OI - Object Index. A table that maps the FID to the object's backend identifier. - For ldiskfs-based backend, this table must be regenerated if restored from - file-level backup. - FID-in-dirent - FID in Directory Entry. To enhance the performance of readdir, the FID of a file is recorded in its directory name entry. +linkEA - Link Extended Attributes. When a file is created or hard-linked the + parent directory name and FID are recorded as extended attributes to the file. + LMA - Lustre Metadata Attributes. A record of Lustre specific attributes, for example HSM state, self-FID, and so on. -linkEA - Link Extended Attributes. When a file is created or hard-linked the - parent directory name and FID are recorded as extended attributes to the file. +OI - Object Index. A table that maps FIDs to inodes. On ldiskfs-based targets, + this table must be regenerated if a file level restore is performed as inodes + will change. + +OSD - Object storage device. A generic term for a storage device with an + interface that extends beyond a block-oriented device interface.