1) Test the eject button to open and close the DVD tray;
2) Put the Solaris media into the drive and check if is normally mounted :
cd /cdrom
ls -la
If drive is working fine,but the iostat -En is still incrementing errors, try to replace the DVD/CD media.
3) If the steps #1 and #2 failed, check /var/adm/messages for erros and collect a new explorer to be sent to Oracle. V890 server is end of support.Oracle will not support it any more.
#cd /opt/SUNWexplo/bin
#./explorer
The output will be at /opt/SUNWexplo/output
4) Reboot the server. Specially if uptime is more than 90 days.
5) Replace the DVD drive.