diff options
Diffstat (limited to 'doc/lvmetad_design.txt')
| -rw-r--r-- | doc/lvmetad_design.txt | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/doc/lvmetad_design.txt b/doc/lvmetad_design.txt index 3b336ec..1961cfb 100644 --- a/doc/lvmetad_design.txt +++ b/doc/lvmetad_design.txt @@ -137,6 +137,17 @@ hosts. Overall, this is not hard, but the devil is in the details. I would possibly disable lvmetad for clustered volume groups in the first phase and only proceed when the local mode is robust and well tested. +With lvmlockd, lvmetad state is kept up to date by flagging either an +individual VG as "invalid", or the global state as "invalid". When either +the VG or the global state are read, this invalid flag is returned along +with the data. The client command can check for this invalid state and +decide to read the information from disk rather than use the stale cached +data. After the latest data is read from disk, the command may choose to +send it to lvmetad to update the cache. lvmlockd uses version numbers +embedded in its VG and global locks to detect when cached data becomes +invalid, and it then tells lvmetad to set the related invalid flag. +dct, 2015-06-23 + Protocol & co. -------------- |