Accusys ExaRAID GUI - Manual (Page 256)

Troubleshooting
6-13
5. It takes too much time for path or controller failover with
MPIO driver
The MPIO driver detects path failure by checking the HBA driver to get
the link status. The setting of HBA determines how much time it takes for
the MPIO driver to detect path failure and to do path failover. If your
controller failover/failback is supported by MPIO drivers, it also determines
how much time it takes for controller failover.
• Qlogic FC HBA BIOS Utility:
Fast!UTIL > Advanced Adapter Settings > Link Down Timeout
Fast!UTIL > Advanced Adapter Settings > Port Down Retry Count
• LSI FC HBA LSI command-line Utility: LSIUtil > Change FC Port settings >
Initiator Device Timeout
Contact your HBA vendor for more information about these settings.
6. Linux pauses for a while during boot-up with dual-controller
system
Because it takes time for Linux to test the standby LUNs of a controller, you
might experience long boot-up time of Linux, but it hurts nothing after the
Linux is running. If you want to reduce the boot-up time, please follow the
procedures below after completing the installation of multi-path driver:
• Edit /etc/modprobe.conf (RedHat) or /etc/modprobe.conf.local
(SUSE 10) to add this line:
options scsi_mod dev_flags=Accusys:ACS92102:0x1000.
• Change to the /boot directory, and build the ramdisk image with the
following command: mkinitrd -f initrd-2.6.[kernel_version].img
[kernel_version] (RedHat), or mkinitrd (SUSE 10)
• Reboot the Linux system
7. Constant path failover or many disk timeout errors reported
at host
Under heavy I/O loading, the operating systems might experience long I/
O response time and falsely report I/O error when the response time is
over its I/O timeout value. The MPIO driver might also be informed of I/O
or path failure and the preferred I/O path would be changed constantly.
This would severely hurt the performance. Extending the I/O timeout
value of your OS or applications can mitigate this problem. For example,
on Windows system, it is advised to set the registry key below to 60 or 90
seconds:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\Time
OutValue.