Using the Iometer Performance Tool (4018642)

This article describes the network testing technique and the sequence of steps that need to be taken to perform network connection testing using the Iometer free network test tool.

In many cases, the replication failure might be due to some environmental or network connection problems. Providing a complete network diagnostics can help to detect the cause of the problem and provide an adequate solution. Quest recommends providing the network connection diagnostic using Iometer free network connection test tool.

Iometer is a test tool that is used to simulate application input/output (I/O) for the purposes of testing storage and storage networking devices. Using Iometer, you can build I/O profiles that simulate the I/O workload that an application or group of applications might perform. Iometer offers many options, but only a few basic configuration options are needed for the purposes of testing iSCSI.

When using the Iometer to test for performance, the more physical disks that the I/O hits, the better the performance. For example, in the case of storage arrays that have RAID capability, the host might see only one LUN but might be actually hitting 10 different physical striped disks, you want the Iometer to hit as many LUNs (drives) as it can.

I/O testing tools like Iometer are normally used to simulate actual application I/O patterns (e.g. Microsoft SQL, Microsoft Exchange). Some of these I/O characteristics, including I/O randomness, read or write operations, and block sizes, all depend on the specific application requirements. Most applications perform read and write operations to a Windows file system and not directly to a raw disk device. Windows NT File System (NTFS) is the most common file system in the Windows operating system; therefore, it is necessary to understand the logical block size or cluster size (in Microsoft terminology) of NTFS. In general, smaller cluster sizes are more storage efficient, but they also slow down drive I/O performance because of the high numbers of I/O threads.

The following table shows the default cluster size of NTFS depending on the partition size (sector = 512 B) for optimal storage efficient and I/O performance.