My Oracle Support Banner

VKTM - High CPU Usage On Linux Hosts / Database Fails to Start (Doc ID 2397170.1)

Last updated on SEPTEMBER 16, 2019

Applies to:

Oracle Database Cloud Service - Version N/A and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Linux x86-64

Symptoms

This issue can manifest in several ways:

VKTM process consumed high CPU resources / degraded host response.

or

Database fails to start with DBWR having long IO waits

or

Database slow to start

 

The issue is specifically targeted at systems using Veritas product for their LUN / cluster management; therefore using Veritas ODM library with the Oracle Database.

Validation of the issue can be done through checking one of these methods:

 

1. These tunable parameters from Doc ID 1992652.1 have no effect: 

_timer_precision : This sets how frequently (in milliseconds) VKTM wakes up and gets the time value.

_disable_highres_ticks : This disabled high resolution VKTM. With this set to TRUE, VKTM would only update every 100 milliseconds.

 

2. DBWR pstack/errorstack may contain:

<- skgfrgblknm <- skgfrgblkdev <- ksfdstblkini <- ksfdfstinifib <- ksfdfstini <- ksfdopn1 <- ksfdopn <- kcfbid <- kcfida <- ksbabs <- ksbrdp

 

3. The Database host has a large number of luns assigned (checking /proc/partitions in LINUX > ~10000)

Changes

 Adding of LUN's to host

Cause

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!


In this Document
Symptoms
Changes
Cause
Solution
References


My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.