Accusys ExaSAN SW-08 - Manual (Page 86)

Appendices
User Guide Page 8.4-1
Appendices
Appendix A: Customer Service and Technical Support
A.1 FAQs
1. Q: Why is it that I have turned on my host system(s), the ExaSAN SW04/08 switch, and the ExaSAN
RAID system(s), but I cannot see any of the newly created Volume on disk?
A: There are two likely probable causes:
a. You did not follow the proper procedures when you turned on your system components.
Please first follow the instructions in Section 3.2.2, “Powering Off,” to turn off all your
system components. Then follow the instructions in Section 3.2.1, “Powering On,” to turn on
all components again.
b. You do not have the latest version of switch firmware installed. Please refer to Section 4.2.3,
“Updating SW04/08 Switch Firmware,” for instructions on how to download and install the
most up-to-date firmware.
2. Q: Why is it that my system performance does not seem to reach the expected level?
A: There are two probable causes:
a. If only one or more, but not all, of your host systems seem to be suffering from lower-than-
expected performance; this host system might not meet the recommended PCIe 2.0 x4
interface specification. Please verify that the host system PCIe slot where the HBA card is
installed is PCIe x4 or better.
With the PCIe 1.0 standard, each data lane has a maximum transmission rate of 250MB/sec.
That means a theoretic 1000MB/sec (250MB/sec times 4) for a x4 slot. However, due to the
fact that the PCIe transmission can only utilize 80% of this bandwidth, the actual maximum
throughput is only 800MB/sec (1000MB/sec times 80%). By the same reasoning, a PCIe 2.0
x4 slot, which is at 500MB/sec per lane, can reach a maximum throughput of 1600MB/sec.
Refer to Section 3.1.2, “Installing the HBA Cards,” for additional information.
b. If the PCIe slot in question meets the recommended hardware specification, you might be
having trouble with your hard drive in the RAID system(s). Please refer to the appropriate
user documentation for your particular RAID storage system, for information on how to use
the “RAIDGuard X” user interface to produce a hard drive log for analysis.
3. Q: How do I verify that the PCIe slot on my host system supports the PCIe2.0 x4 standard or better?
A: There are two possibilities: