标题: RAC的幾個特殊的進程 [打印本页] 作者: gkl0818 时间: 2008-12-4 09:59 标题: RAC的幾個特殊的進程 LMS Global cache service processes (LMSn) are processes that, when spawned by Oracle, copy blocks directly from the holding instance's buffer cache and send a read consistent copy of the block to the reques ting foreground process on the requesting instance to be placed into the buffer cache. LMS rolls back any uncommitted transactions for any blocks that are being requested for consistent read by the remote instance.
RAC software provides for up to 10 LMS processes (0–9), depending on the amount of messaging traffic. However, there is, by default, one LMS process per pair of CPUs. In general, the number of LMS processes varies depending on the amount of messaging traffic amongst nodes in the cluster. LMON The global enqueue service monitor (LMON) is a background process that monitors the entire cluster to manage global resources. By constantly probing the other instances, it checks and manages instance deaths and the associated recovery for GCS. When a node joins or leaves the cluster, it handles reconfiguration of locks and resources. In particular, LMON handles the part of recovery associated with global resources. LMON provided services are also known as cluster group services (CGS). LMD The global enqueue service daemon (LMD) is a background agent process that manages requests for resources to control access to blocks and global enqueues. It manages lock manager service requests for GCS resources and sends them to a service queue to be handled by the LMSn process. The LMD process also handles global deadlock detection and remote resource requests (remote resource requests are requests originating from another instance). GSD The global service daemon (GSD) is a component that receives requests from the SRVCTL control utility to execute administrative job tasks such as startup or shutdown. The command is executed locally on each node and the results are returned to SRVCTL. The GSD is installed on the nodes by default. LCK The lock process (LCK) manages non-cache fusion resource requests such as library and row cache requests and lock requests that are local to the server. LCK process manages instance resource requests and cross-instance call operations for shared resources. It builds a list of invalid lock elements and validates lock elements during recovery. Because the LMS process handles the primary function of lock management, only a single LCK process exists in each instance. DIAG The diagnosability daemon (DIAG) background process monitors the health of the instance and captures diagnostic data about process failures within instances. The operation of this daemon is automated and updates an alert log file to record the activity that it performs.