From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bob Peterson Date: Thu, 13 Aug 2009 11:13:46 -0400 (EDT) Subject: [Cluster-devel] GFS2 and uevents document In-Reply-To: <354693629.557911250176397806.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> Message-ID: <530138690.557931250176426956.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit ----- "Steven Whitehouse" wrote: | Hi, | | Below is a first draft at a document explaining the uevents produced | by | GFS2. I'm intending to add it under | linux-2.6/Documentation/filesystems/gfs-uevents.txt | | Let me know if you spot anything thats wrong or could be better | explained, | | Steve. Hi Steve, Good writeup. Here are some minor suggestions. Bob Peterson -- --- /home/msp/rpeterso/gfs_uevents.orig.txt 2009-08-13 10:02:25.000000000 -0500 +++ /home/msp/rpeterso/gfs_uevents.bobs.txt 2009-08-13 10:10:33.000000000 -0500 @@ -1,9 +1,9 @@ uevents and GFS2 ================== -During the lifetime of a GFS2 mount, a number of uevents are generated, -this document explains what the events are and what they are used -for (by gfs_controld in gfs2-utils) +During the lifetime of a GFS2 mount, a number of uevents are generated. +This document explains what the events are and what they are used +for (by gfs_controld in gfs2-utils). A list of GFS2 uevents ----------------------- @@ -12,26 +12,26 @@ A list of GFS2 uevents The ADD event occurs at mount time. It will always be the first uevent generated by the newly created filesystem. If the mount -is successful, an ONLINE uevent will follow, if it is not successful +is successful, an ONLINE uevent will follow. If it is not successful then a REMOVE uevent will follow. The ADD uevent has two environment variables: SPECTATOR=[0|1] -and RDONLY=[0|1] which specify the spectator (no journal assigned, -implies a read-only mount) and read-only status of the filesystem -respectively. +and RDONLY=[0|1] that specify the spectator status (a read-only mount +with no journal assigned), and read-only (with journal assigned) status +of the filesystem respectively. 2. ONLINE The ONLINE uevent is generated after a successful mount or remount. It has the same environment variables as the ADD uevent. The ONLINE uevent, along with the two environment variables for spectator and -rdonly are a relatively recent addition (2.6.32-rc+) and will not +RDONLY are a relatively recent addition (2.6.32-rc+) and will not be generated by older kernels. 3. CHANGE The CHANGE uevent is used in two places. One is when reporting the -sucessful mount of the filesystem by the first node (FIRSTMOUNT=Done). +successful mount of the filesystem by the first node (FIRSTMOUNT=Done). This is used as a signal by gfs_controld that it is then ok for other nodes in the cluster to mount the filesystem. @@ -40,7 +40,7 @@ of journal recovery for one of the files two environment variables, JID= which specifies the journal id which has just been recovered, and RECOVERY=[Done|Failed] to indicate the success (or otherwise) of the operation. These uevents are generated -for every journal recovered whether it is during the initial mount +for every journal recovered, whether it is during the initial mount process or as the result of gfs_controld requesting a specific journal recovery via the /sys/fs/gfs2//lock_module/recovery file. @@ -79,7 +79,7 @@ able to join the cluster. 2. LOCKPROTO= -The LOCKPROTO is a string, again its value depends on that set +The LOCKPROTO is a string, and its value depends on what is set on the mount command line, or via fstab. It will be either lock_nolock or lock_dlm. In the future other lock managers may be supported. @@ -93,7 +93,7 @@ numeric journal id in all GFS2 uevents. 4. UUID= With recent versions of gfs2-utils, mkfs.gfs2 writes a UUID -into the filesystem superblock. If it exists, then this will +into the filesystem superblock. If it exists, this will be included in every uevent relating to the filesystem.