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
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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