M A G M A
Iometer® is a software-based I/O exerciser capable to test and characterize stand-alone as well as clustered storage systems. Developed originally by Intel as a proprietary tool, it eventually became part of the Open Source Development Lab (OSDL) from which point it has undergone several revisions and updates.
Going back to the Fibre channel host controller cards, one of the features that the ATTO FC-44ES supports is the creation of multiple, small virtual drives that can be striped by the OS for faster access. What that translates to is the ability of two cards to communicate amongst themselves at the fastest possible rate, unaffected by delays otherwise encountered by moving parts in an actual disk drive.
By using this method combined with the Iometer® application, one can benchmark
the communication channel and verify that the PCIe express link is utilized to its fullest potential.
In the example below, a single ATTO FC-44ES card was installed into one of the 4 PCIe expansion slots provided by the EB2 chassis. It was then connected via fiber optic cables to a second FC-44ES card (set to simulate a fibre disk array, by using a striped set of small virtual drives ). Three tests were performed using Iometer. In the first, an equal amount of read and write threads were exercised between the two cards. The following two tests focused on either all-read or all-write threads. The test results are shown in the table below:
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| I/O Test type | Throughput [MByte/sec] |
| 50% Reads; 50% Writes | 1003.3 |
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| | |
| 100% Reads | 696.1 |
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| 100% Writes | 677.7 |
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The results show an aggregate throughput exceeding 1GByte in the case where reads and writes are evenly split 50-50 and a slower, more realistic rate when only a single type of threads was exercised.
