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"dd" Read From ACFS Filesystem Is Slow (Doc ID 2122848.1)

Last updated on JANUARY 24, 2020

Applies to:

Oracle Database - Enterprise Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.


We use ACFS filesystem to store Goldengate trail files on OGG source and target side.

"dd" read test result
ACFS read speed OGG volume disk volume disk speed
OGG source 71MB/s /dev/asm/ggatevol-40 7MB/s                      <<----------- 71 MB/s
OGG target 4.5MB/s /dev/asm/ggate-50 15MB/s                         <<-----------4.5 MB/s

Need to identify the root cause why "dd" read on OGG target side is slow.
$ time dd if=gg001649 of=/dev/null ibs=30000 obs=4096 count=17067 ( read 500MB trail file)
real 1m50.32s 500MB/(1m50seconds) = 4.5MB/second                   <<--------- 4.5 MB/s
user 0m1.81s
sys 0m2.49s


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