Applies to:
Oracle Server – Enterprise Edition – Version: 11.2.0.2 to 11.2.0.2
Information in this document applies to any platform.
Purpose
This article provides information on some new background proccesses introduced in 11gR2 by a new product ACFS (ASM Cluster Filesystem).
Scope and Application
The intended audience of this bulletin is DBAs, System Administrators who are responsible for managing the 11gR2 ASM and ACFS. It is assumed that the reader of this document has knowledge of basic concepts of ASM and ACFS.
New Background Processes introduced by ACFS
Since 11gR2, Oracle introduces a new product, ASM Cluster Filesystem, or ACFS. This has introduced several new ASM instance Background proccesses. A ps -ef output of these proccesses shows:
oracle 4282 1 0 09:54 ? 00:00:00 asm_vdbg_+ASM1
oracle 4284 1 0 09:54 ? 00:00:00 asm_vmb0_+ASM1
oracle 4362 1 0 09:54 ? 00:00:00 asm_vbg1_+ASM1
oracle 4365 1 0 09:54 ? 00:00:00 asm_vbg2_+ASM1
oracle 3962 1 0 09:54 ? 00:00:00 asm_acfs_+ASM1
1). Volume Driver Background (VDBG) process:
oracle 4282 1 0 09:54 ? 00:00:00 asm_vdbg_+ASM1
This process acts like the Umbilicus Foreground (UFG) for a database ASM client. It will forward ASM requests to lock/unlock an extent for rebalancing, volume resize, disk offline, add/drop disk, force dismount diskgroup, etc to the ADVM driver. The VDBG is a fatal background process so the unplanned death of this process will bring down the ASM instance.
2). Volume Background (VBG#) processes
oracle 4362 1 0 09:54 ? 00:00:00 asm_vbg1_+ASM1
oracle 4365 1 0 09:54 ? 00:00:00 asm_vbg2_+ASM1
These are a pool of worker background processes which will wait in the ADVM driver for requests from the ADVM driver which need to be coordinated with the ASM instance. An example of such a request would be opening/closing an ADVM dynamic volume file when the ADVM driver receives an open for an ADVM special device file (possibly due to a filesystem mount request) or close for an open ADVM device special file (possibly due to a filesystem unmount request). The unplanned death of any of these processes will have no effect on the ASM instance.
3). Volume Membership Background (VMB) processes
oracle 4284 1 0 09:54 ? 00:00:00 asm_vmb0_+ASM1
The VMB process provides the role of an IO barrier/IO fencing function. In the event of an ASM instance failure, this process continues to exist until the ADVM driver has had a chance to write out IO pending IOs.
4). acfs background process
oracle 3962 1 0 09:54 ? 00:00:00 asm_acfs_+ASM1
The acfs background process within ASM manages all of the clusterware membership and state transitions.
Related Posts