I/O performance reduced on RHEL 6 with Symantec Storage Foundation SF 6.0.1
dd to write to the entire length of a test device is significantly slower on Red Hat Enterprise Linux (RHEL) 6, when upgrading to Symantec Storage Foundation version 6.0.1.
This is a known issue detailed in the following Symantec knowledge-base article. Please contact Symantec directly for up-to-date recommendation on how to remedy this issue. Please note, the following link is external to Red Hat and as such, we cannot validate its contents:
Performance degradation observed when running Storage Foundation 6.0.x on RHEL 6.x
It is possible to test I/O performance to Veritas disk groups by writing to the length of a device through something similar to the following
dd command. It is necessary to include
oflag=direct so that data is written directly to the disk in order to avoid results being skewed through the use of caching:
dd if=/dev/zero of=/dev/vx/<etc> bs=64k count=<length_of_disk_in_blocks> oflag=direct
NOTE: Please run this command on test devices only as this will overwrite the contents of the target device.