[Ocfs2-tools-commits] smushran commits r1192 - trunk/documentation

[svn-commits@oss.oracle.com]

Author: smushran
Date: 2006-05-03 18:03:41 -0500 (Wed, 03 May 2006)
New Revision: 1192

Added:
   trunk/documentation/process.txt
Modified:
   trunk/documentation/ocfs2_faq.txt
Log:
Processes added in faq

Modified: trunk/documentation/ocfs2_faq.txt
===================================================================
--- trunk/documentation/ocfs2_faq.txt	2006-05-02 01:36:01 UTC (rev 1191)
+++ trunk/documentation/ocfs2_faq.txt	2006-05-03 23:03:41 UTC (rev 1192)
@@ -750,3 +750,76 @@
 	by setting "SELINUX=disabled" in /etc/selinux/config. Change
 	is activated on reboot.
 ==============================================================================
+
+Processes
+---------
+
+Q01	List and describe all OCFS2 threads?
+A01	[o2net]
+	One per node. Is a workqueue thread started when the cluster is
+	brought online and stopped when offline. It handles the network
+	communication for all threads. It gets the list of active nodes
+	from the o2hb thread and sets up tcp/ip communication channels
+	with each active node. It sends regular keepalive packets to
+	detect any interruption on the channels.
+
+	[user_dlm]
+	One per node. Is a workqueue thread started when dlmfs is loaded and
+	stopped on unload. (dlmfs is an in-memory file system which allows user
+	space processes to access the dlm in kernel to lock and unlock
+	resources.) Handles lock downconverts when requested by other
+	nodes.
+
+	[ocfs2_wq]
+	One per node. Is a workqueue thread started when ocfs2 module is
+	loaded and stopped on unload. Handles blockable file system tasks
+	like truncate log flush, orphan dir recovery and local alloc
+	recovery, which involve taking dlm locks. Various code paths
+	queue tasks to this thread. For example, ocfs2rec queues orphan
+	dir recovery so that while the task is kicked off as part of
+	recovery, its completion does not affect the recovery time.
+
+	[o2hb-14C29A7392]
+	One per heartbeat device. Is a kernel thread started when the
+	heartbeat region is populated in configfs and stopped when it
+	is removed. It writes every 2 secs to its block in the heartbeat
+	region to indicate to other nodes that that node is alive. It also
+	reads the region to maintain a nodemap of live nodes. It notifies
+	o2net and dlm any changes in the nodemap.
+
+	[ocfs2vote-0]
+	One per mount. Is a kernel thread started when a volume is mounted
+	and stopped on umount. It downgrades locks when requested by other
+	nodes in reponse to blocking ASTs (BASTs). It also fixes up the dentry
+	cache in reponse to files unlinked or renamed on other nodes.
+
+	[dlm_thread]
+	One per dlm domain. Is a kernel thread started when a dlm domain
+	is created and stopped when destroyed. This is the core dlm
+	which maintains the list of lock resources and handles the
+	cluster locking infrastructure.
+
+	[dlm_reco_thread]
+	One per dlm domain. Is a kernel thread which handles dlm recovery
+	whenever a node dies. If the node is the dlm recovery master, it
+	remasters all the locks owned by the dead node.
+
+	[dlm_wq]
+	One per dlm domain. Is a workqueue thread. o2net queues dlm
+	tasks on this thread.
+
+	[kjournald]
+	One per mount. Is used as OCFS2 uses JDB for journalling.
+
+	[ocfs2cmt-0]
+	One per mount. Is a kernel thread started when a volume is
+	mounted and stooped on umount. Works in conjunction with
+	kjournald.
+
+	[ocfs2rec-0]
+	Is started whenever another node needs to be be recovered. This
+	could be either on mount when it discovers a dirty journal or
+	during operation when hb detects a dead node. ocfs2rec handles
+	the file system recovery and it runs after the dlm has finished
+	its recovery.
+==============================================================================

Added: trunk/documentation/process.txt
===================================================================
--- trunk/documentation/process.txt	2006-05-02 01:36:01 UTC (rev 1191)
+++ trunk/documentation/process.txt	2006-05-03 23:03:41 UTC (rev 1192)
@@ -0,0 +1,71 @@
+Processes
+---------
+
+Q01	List and describe all OCFS2 threads?
+A01	[o2net]
+	One per node. Is a workqueue thread started when the cluster is
+	brought online and stopped when offline. It handles the network
+	communication for all threads. It gets the list of active nodes
+	from the o2hb thread and sets up tcp/ip communication channels
+	with each active node. It sends regular keepalive packets to
+	detect any interruption on the channels.
+
+	[user_dlm]
+	One per node. Is a workqueue thread started when dlmfs is loaded and
+	stopped on unload. (dlmfs is an in-memory file system which allows user
+	space processes to access the dlm in kernel to lock and unlock
+	resources.) Handles lock downconverts when requested by other
+	nodes.
+
+	[ocfs2_wq]
+	One per node. Is a workqueue thread started when ocfs2 module is
+	loaded and stopped on unload. Handles blockable file system tasks
+	like truncate log flush, orphan dir recovery and local alloc
+	recovery, which involve taking dlm locks. Various code paths
+	queue tasks to this thread. For example, ocfs2rec queues orphan
+	dir recovery so that while the task is kicked off as part of
+	recovery, its completion does not affect the recovery time.
+
+	[o2hb-14C29A7392]
+	One per heartbeat device. Is a kernel thread started when the
+	heartbeat region is populated in configfs and stopped when it
+	is removed. It writes every 2 secs to its block in the heartbeat
+	region to indicate to other nodes that that node is alive. It also
+	reads the region to maintain a nodemap of live nodes. It notifies
+	o2net and dlm any changes in the nodemap.
+
+	[ocfs2vote-0]
+	One per mount. Is a kernel thread started when a volume is mounted
+	and stopped on umount. It downgrades locks when requested by other
+	nodes in reponse to blocking ASTs (BASTs). It also fixes up the dentry
+	cache in reponse to files unlinked or renamed on other nodes.
+
+	[dlm_thread]
+	One per dlm domain. Is a kernel thread started when a dlm domain
+	is created and stopped when destroyed. This is the core dlm
+	which maintains the list of lock resources and handles the
+	cluster locking infrastructure.
+
+	[dlm_reco_thread]
+	One per dlm domain. Is a kernel thread which handles dlm recovery
+	whenever a node dies. If the node is the dlm recovery master, it
+	remasters all the locks owned by the dead node.
+
+	[dlm_wq]
+	One per dlm domain. Is a workqueue thread. o2net queues dlm
+	tasks on this thread.
+
+	[kjournald]
+	One per mount. Is used as OCFS2 uses JDB for journalling.
+
+	[ocfs2cmt-0]
+	One per mount. Is a kernel thread started when a volume is
+	mounted and stooped on umount. Works in conjunction with
+	kjournald.
+
+	[ocfs2rec-0]
+	Is started whenever another node needs to be be recovered. This
+	could be either on mount when it discovers a dirty journal or
+	during operation when hb detects a dead node. ocfs2rec handles
+	the file system recovery and it runs after the dlm has finished
+	its recovery.