Product Roundup: Intel/LSI RAID cards

Introduction

A RAID can give either data security or amazing performance depending on the type of array that is used. With the recent leaps in performance of solid state drives however, some RAID cards are starting to show their limitations. Today we will be looking at the performance of five RAID cards across a broad spectrum of classes; from budget cards to high-end cards.  Three of the cards are from LSI (budget to mid range) and two are from Intel (high-end).

LSI 9211-4i Host Bus Adapter Line	LSI 9240-4i MegaRAID Entry Line	LSI 9750-4i 3ware Line

Intel RS2BL040 Mainstream Line	Intel RS2BL080 MainStream Line

RAID Card Specs

	LSI 9211-4i	LSI 9240-4i	LSI 9750-4i	Intel RS2BL040	Intel RS2BL080
# of ports	4	4	4	4	8
Software	LSI MegaRAID	LSI MegaRAID	3ware 3DM2	Intel RAID  Web Console	Intel RAID  Web Console
Max stripe size	n/a	64K	256K	1MB	1MB
Est. street price	$170	$190	$390	$330	$490
0
1
5
6
10
50

For our testing SSD, we will be using the Intel SSD 510 250GB SATA 6GB/s as our RAID drive. This is a very fast drive and should show us any speed limitations present on any of the RAID cards.  We will be using CrystalDiskMark as our benchmarking program. This article will be exclusively focused on performance, so we will not be going over installation and configuration of the RAID cards/arrays.  Our test system specs are below:
 

Benchmark Results

While these cards support a wide range of RAID levels, we will only be testing RAID 0,1,5 and 10 as they are the most commonly used types. Before we start doing performance benchmarking of the actual RAID's, we will first run a set of benchmarks with just a single drive. For this one configuration, we will also be including the onboard controller. This will help us establish a baseline for the RAID cards as they compare to each other as well as to the onboard controller.

Single Disk

With just a single disk in no RAID configuration, we see that the LSI 9211-4i card is the bottom performer, with roughly a 30-48% drop in performance compared to the onboard controller. The LSI 9750-4i and 9240-4i both perform pretty much on par with the onboard controller. Both Intel controllers have roughly the same write speeds as the onboard, but give a nice boost to read speeds.

RAID 1 (2-disk)

Once again, the LSI 9211-4i is at the bottom. Surprisingly, the LSI 9750-4i is roughly on par with both the high-end Intel RAID cards in the sequential read/write benchmarks. The random read/write scores however are much lower. The LSI 9240-4i is starting to show some problems with write performance, scoring lower than even the LSI 9211-4i in that area.

RAID 0 (2-disk)

In a RAID 0, we have our first 1GB/s result, with the Intel RS2BL080 achieving 1031 MB/s sequential read speed. The LSI 9240-4i continues to show problems with write speeds, but all the other scores are pretty much right where we expect them to be relative to their class.

RAID 0 (4-disk)

Except for the budget-oriented LSI 9211-4i and the lagging write speed on the LSI 9240-4i, all of the cards are achieving over 1GB/s sequential read/write speeds. The sequential read speeds on the Intel cards are not much higher than the 2-disk RAID 0 speeds however, so we suspect that we are starting to get near the top limit of these cards.

RAID 10 (4-disk)

Generally, a 4-disk RAID 10 should have roughly the same performance as a 2-disk RAID 0.  While this appears to be true for most of these RAID cards, the LSI 9211-4i sequential read performance drops by half compared to it's 2-disk RAID 0 score. The sequential write speed also suffers, but by more than a factor of four.

RAID 5 (4-disk)

Since the LSI 9211-4i does not support RAID 5, that card had to sit this round out.  Once again, the LSI 9240-4i is showing a big problem with write performance, but the read performance was better than any of the other cards. For the first time in our testing, the LSI 9750-4i is at the bottom of the stack in regards to read performance, being the only card not above 1000MB/s.

Conclusion

From our testing, we can clearly conclude that the Intel RAID cards are the best performers from this batch, which is what we expected since they are intended to be high-end RAID cards. One thing to keep in mind is that we were using one of the fastest SSD's currently available for our testing. If you are planning on using a traditional platter drive, or a more budget-friendly SSD, some of these results may not matter as much.

Traditionally, the more expensive RAID cards have better management utilities and are more reliable, but since this article is focused primarily on performance, lets consider one potential scenario. Say you have two Western Digital Black 1TB SATA 6Gb/s drives that you want to have in a RAID 1 array. These drives on average perform a bit under 150MB/s on both read and write which we will round up to 150MB/s to make the math easier. A 2-disk RAID 1 (mirror) array will perform roughly at the same speeds as a single drive, so as long as the controller can handle 150MB/s read and write speeds you should not see any performance differences between the cards. From our testing, the LSI 9750-4i, Intel RS2BL040 and the Intel RS2BL080 should all be able to run this configuration without any drop in performance.  
Likewise, if you wanted to use those same two drives in a RAID 0 (stripe) array you should expect about double the speeds of a single drive, or 300MB/s. From our testing, the only card that we tested that would show a performance drop is the LSI 9240-4i due to it's low write speeds.

This is a vastly simplified and broad way to estimate RAID performance since there are many factors that come into play, but for rough estimations it should at least get you into the right ballpark.

Overall, these RAID cards mostly performed right where we expected them to in relation to their class. The LSI 9240-4i did however give disappointing write performance across all the RAID types, although it's read performance was right on target. The LSI 9211-4i also showed performance drops as we tested the larger 4-disk arrays, so we would not recommend using that card for anything larger than a 2-disk array. Both the Intel cards were at or near top performance in all of our testing, making them our recommended card for those that need top performance.