ATTO Technology 2700C Checking the Ethernet host adapter or NIC, Checking applications

3Verify that packets are not being dropped along the LAN/WAN. Many utilities track packet activity and switch statistics.

Checking the Ethernet host adapter or NIC

Ethernet storage adapters generally outperform accelerated NICs and un-accelerated NICs by offloading most of the processing from the host.

An accelerated NIC provides some offloading, but still requires a host OS iSCSI driver, making the host spend more CPU cycles.

An un-accelerated NIC does not offload anything so the CPU must do much of the processing.

1Verify that the adapter or NIC is sent to auto- negotiate or forced to 1000 Mbs.

2Set the MTU size to the largest MTU size supported in the LAN/WAN using the Ethernet page in the ATTO ExpressNAV interface.

9k frame size is the current optimized frame size for the iPBridge. Smaller frame sizes cause a decrease in performance. Many switch and router vendors do not support the larger frame size of 9k or 16k.

3Set the maximum transfer size to the most efficient size for the intended target(s). For many tape drives, 64k is the optimal setting.

Checking applications

Some applications can be configured to change transfer sizes. Configure the application for the optimal size for the particular device(s) connected to the iPBridge.

Checking the host system

The faster the host, the faster your transfer times will be. The work flow goes only as fast as the slowest connection in the host system, so transferring data from an IDE drive, 100Mb connection, a DLT 4000, a high speed RAID volume across the country, or other

applications, slows the system no matter how fast everything else is in the system.

1Verify that the iSCSI storage adapter or NIC is connected to the fastest PCI bus connector supported by the adapter or NIC.

If the adapter supports PCI-X, place the adapter in a PCI-X slot. If one is not available, the host might not achieve the optimal performance capable from the adapter.

Even placing a PCI-X adapter into a 64 bit 66 MHz slot loses performance. Some adapters adjust clock speed depending on the speed of the PCI slot into which they are plugged.

2The host OS disk and swap disk/partition/file should be on a high speed drive to minimize the time needed to access the host’s virtual memory.

The more memory a system has, the less time it spends accessing virtual memory (hard drive space).

Checking the Operating System

If possible, eliminate swap space and virtual drives which require large amounts of system memory. However, the OS might not allow the elimination of swap space. An OS set to run many kinds of different servers spends much of its CPU cycles on other operations, thus slowing down performance.

Optimizing ATTO ExpressNAV in Internet Explorer

1Go to the browser toolbar and select Tools

2Select Internet Options

3Select the Security tab

4Select the Custom Level button.

5On the menu presented, go to the Microsoft VM, Java permissions and make sure Disable Java is not selected.

6Go to the Miscellaneous topic and select

METAREFRESH.

30 Troubleshooting