LSI MegaRAID 9265-8i
According to LSI, SMEs (small and medium enterprises) are the target audience for its MegaRAID 9265-8i. The company markets the card as well-suited for cloud, security, and business applications. With a street price of approximately $630, the MegaRAID 9265-8i is the most expensive controller in this test, but as the benchmark results show, you get what you pay for. Before we present the benchmark results, let’s discuss this controller's technical features and its optional software add-ons called FastPath and CacheCade.
The LSI MegaRAID 9265-8i is based on a dual-core LSI SAS2208 ROC, employing an eight-lane PCIe 2.0 interface. The suffix -8i in the product name denotes eight internal SATA/SAS ports, each of which supports 6 Gb/s. Up to 128 physical storage devices can be connected to the controller via SAS expanders. The low-profile card also features 1 GB DDR3-1333 cache, and supports RAID levels 0, 1, 5, 6, 10, and 60.
Tuning Tools, FastPath, and CacheCade
LSI claims that FastPath can dramatically accelerate the I/O operations of attached SSDs. The company says the FastPath feature works with any flash-based SSD, markedly improving the read/write performance of a SSD-based RAID array by up to 2.5x in writes and up to 2x in reads, achieving 465 000 IOPS. We weren't even able to put that to the test, though. As delivered, this card already had enough horsepower to handle our five-drive SSD array without FastPath installed.
The other software option for the MegaRAID 9265-8i is called CacheCade. It enables the use of one SSD as a read cache for an array of hard disks. According to LSI, this may accelerate read operations by a factor of up to 50, depending on the size of the data being accessed, the application, and the use case. We tried this tool out and created a RAID 5 array consisting of seven hard disks and one SSD (the SSD serving as a read cache). Compared to a RAID 5 setup composed of eight hard disks, it's evident that CacheCade not only improves measured I/O throughput, but even perceived performance (increasingly so as the original data set becomes smaller). We used a 25 GB data set for our test and achieved 3877 IOPS in the Web server Iometer workload, whereas a normal hard disk-based array was only able to hit 894 IOPS.
Performance
In a nutshell, LSI's MegaRAID 9265-8i is the fastest SAS RAID controller in this round-up with respect to I/O performance. As far as sequential read/write operations go, however, the controller only achieves mid-range performance, as its sequential performance varies greatly depending on the RAID level you use. In the RAID 0 hard disk test, we see sequential reads of up to 1080 MB/s (significantly faster than the competitors). Sequential write performance in RAID 0, 927 MB/s, takes a first-place finish, too. In RAID 5 and 6, however, the LSI controller is beaten by all of the other contenders, only redeeming itself in the RAID 10 benchmarks. In the SSD RAID test, LSI's MegaRAID 9265-8i posts the best sequential write performance (752 MB/s) and is only beaten by the Areca ARC-1880i in sequential reads.
If you are looking for an SSD-oriented RAID controller with high I/O performance, the LSI controller is a winner. With rare exceptions, it winds up in first place in our Iometer database, file server, Web server, and workstation workloads. When your RAID array consists of SSDs, LSI's contender is truly unleashed. It utterly outclasses the three other controllers. For example, in the workstation benchmark, the MegaRAID 9265-8i achieves 70 172 IOPS, while the second-place finisher, Areca's ARC-1880i, posts slightly more than half that number, 36 975 IOPS.
