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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


This issue can manifest in several ways:

VKTM process consumed high CPU resources / degraded host response.


Database fails to start with DBWR having long IO waits


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)


 Adding of LUN's to host


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