RAID 0

Of course, even for the simplest array there should be at least 2 HDDs involved. However, controller cards can work with a single HDD as well. When we connected one hard disk drive to Promise FastTrak100 and AMI HyperDisk100 controllers, they announced it was a RAID 0 array. That is why we added here the results obtained for a single hard drive.

3ware Escalade 6400

To begin with, let's take a closer look at the results obtained in Drive 1.0:

We would like to share one interesting observation with you: all the parameters are gradually improving up to 3HDD and get a little bit lower for 4HDD. Note that the max liner read rate made only 40.2MB/sec. Even though there were three IBM DTLA 307015 HDDs connected to the controller, each of which is capable of providing the read rate of 37MB/sec. Well, this is where working via cache tells. But maybe we are wrong, and it is the problem with the benchmark? Let's take a look at the results obtained in HDTach:

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Hm, strange things keep happening. The average read rate drops down as the number of HDDs grows, and the write rate, on the contrary, rushes up. Does it mean that reading goes via the cache buffer and writing doesn't? The data transfer rate to and from the cache remains constant and is equal to approximately 45MB/sec. Moreover, it doesn't depend on the number of hard disk drives involved. The average access time however, is a bit lower than in case of a single HDD, which is quite logical.

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Yes, finally, no more problems with the linear transfer rate! Just look at the linear read graphs: what a thing! It turns out that Drive and HDTach can't work with this controller properly, that's it. The only parameter, which remains the same for all the three benchmarks, is average access time.

Now let's see how things in NTFS stand:

In NTFS the performance drops a bit when the second HDD is added. Then it takes on, though the results shown by a single hard drive still remain the best. In High-End benchmark, the results also drop down for 2HDDs case but then they grow up pretty rapidly.

A considerable difference between the cluster size (4KB) and stripe-block size (64KB) results into very poor parallel operation of the HDDs forming an array. And if there they don't work in parallel, then using this type of storage subsystem organization doesn't make much sense. At the same time, switching between the HDDs too often also leads to the performance lowering.

Now it's the turn of Intel IOMeter. Let's sum up all the Total I/O for all patterns in one table:

Since in the first place we are interested in checking the controller's performance under heavy workload, we decided to make up a diagram showing the dependence of the Total I/O for each pattern under Heavy load on the number of HDDs involved:

Well, the graphs are pretty typical, we should say. Almost for all patterns you can see some nearly linear dependence on the number of drives in the array. Look at the SequentialWrite graph: we can see two intervals made by 1-2 HDDs and 3-4 HDDs. Between them the tempo slows down noticeably. In other words, when the second AccelerATA chip is activated, the performance of the DiskSwitch chip is no longer enough. Anyway, despite all this criticism, the controller manages to transfer almost 80MB/sec in this mode, which is quite impressive.

Adaptec AAA-UDMA

Just as in the previous case, let's start from Drive 1.0 benchmark:

And again just as in the previous case the results are very strange. Now let's forget everything except Average Access Time and pass over to HDTach 2.61:

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Please, take a look at the average write speed. It doesn't depend on the number of hard drives connected at the moment and is limited only by the controller performance. it is most likely to be caused by the slow cache or slow chip responsible for data transfer to and from the cache.

The average read speed reaches its peak value (is it the maximum for this controller?) in case of 2 HDDs and then starts reducing. Maybe the bus got overloaded with some auxiliary info, which affected the performance so much? Hm… and what kind of bus is that then? There is only one chip on this controller card managing the connection to all hard disk drives. This seems to be the problem actually: the chip is simply unable to handle the hard drives that fast.

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Thank goodness, we can now see that the results obtained depend linearly on the number of connected hard disk drives. But the growth is again very low. The linear read graphs illustrate very well the maximum bandwidth of the controller. If we connect 1 HDD to the controller, the graph will look ordinarily. However, as soon as the second HDD appears, we will notice that the read speed doesn't exceed 45/46MB/sec.

The results in Business and High-End reach the top in a three-drive array. Then they start getting lower.

Now we are passing to Intel IOMeter.

The results can hardly be called impressive.

The controller proves scalable only in RandomWrite. In all other patterns adding more hard drives doesn't tell on the performance that much.

Promise SuperTrak100

Frankly speaking, we have nearly lost all hope now to see something acceptable in Drive 1.0. But let's take another try, anyway:

As far as the linear read speed goes, no comments here. But the average access time has suddenly risen by 1msec. Since we have observed almost similar results in Drive, HDTach and WinBench, we assume that the access time growth in Drive test should be also noticeable in HDTach.

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The HDTach tests also showed that the average access time for RAID 0 by Promise controller is a bit higher than by 3ware and Adaptec ones.

Again the more hard disk drives are involved in the array, the higher gets the write speed and the lower appears the read speed. Although, in case of a 2-HDD array the average write speed turned out extremely low, you will understand what we are driving at when you take a closer look at the graph.

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Judging by the results obtained in Disk Transfer Rate test, this controller turns out to have even lower bandwidth than Adaptec AAA-UDMA. The maximum linear read rate it showed made only 20.3MB/sec.

In the integral tests the situation appeared really interesting. In Business Disk Winmark the performance peak was detected in a two-drive array. Then the performance dropped a lot, and with every other hard disk drive added grew a little bit. In High-End Disk Winmark we can see that the performance grows gradually little by little.

In NTFS the peak in Business Winmark is again achieved on an array composed of two hard drives and the results in High-End Winmark grow with the every new HDD added.

Now comes Intel IOMeter test:

Well, what could we say here? The results are far from being brilliant. Now let's see how it will all look on a graph:

Terrific! There appeared some limitations even for a RandomWrite pattern this time. And the results for three hard disk drives united into an array appeared better than for four hard disk drives, which means that even a multi-chip solution has its bottlenecks.

The most predictable results were obtained for SequentialWrite pattern: the performance grew up very slowly and got limited by the controller bandwidth (20MB/sec).

Controllers Comparison

In fact, it doesn't make much sense to compare the controllers with each other in low-end tests. As we have discovered, according to the tests the bandwidth of Promise and Adaptec controllers is limited during reads and only 3ware controller shows the increase in performance as the number of the drives connected grows. Therefore, we suggest passing over to WinBench99 right away:

Adaptec and 3ware controllers show similar performance growth depending on the number of HDDs involved, while Promise controller suddenly faced some problems. The maximum performance it managed to achieve was that obtained for dual-drive array. Then the results simply collapse and after that we can notice a slight gradual growth again.

In High-End tests the amount of processed data increases and we see that the performance of Adaptec and Promise controllers is restricted by slower cache memory. 3ware, however, shows a much more rapid performance rise following the increasing number of hard disk drives in the array. But judging by the graph, its results are also very likely to get close to the asymptote when working with 6 HDDs (we could have checked that out if we had had Escalade 6800 at our disposal, which is equipped with 4 AccelerATA chips and is capable of working with 8 HDDs).

Beautiful scenery, don't you think so? The graphs for Adaptec and Promise controllers again go in parallel, except Promise SuperTrak100 for 3 HDDs, where something bad happened to it. Well, let's regard it as a testing error… If it were not for this error, Promise controller (just like Adaptec AAA-UDMA) could reach its maximum for 3 HDDs case. And every other HDD connected to it could only worsen the results. In fact there is nothing to be surprised at or frightened of. Not in every case the controller is requested, the configuration with more HDDs proves faster.

And 3ware controller has suddenly slowed down its pace. Why so? Is it the problem with the drivers or a dislike of small clusters? If every chip uses its own selected part of the memory, the thing may really turn out a problem.

Well, to our great disappointment we have to admit that in WinBench all controllers performed just the same was as a single HDD did. Actually, this fact once again proves that the controllers we are considering here were never intended for work in desktop systems.

And now let see how they managed to cope with server tests:

We can clearly see that in FileServer, WorkStation and DataBase patterns the controllers from Promise and Adaptec appear absolutely helpless… The performance appears comparable to a single IDE drive running, and as for the comparison with some SCSI system, you'd better forget about it once and for all. It seems to be slower cache memory that tells, because in RandomWrite pattern (where the controllers do only write operations) all the testing participants showed fine performance growth. Although Promise SuperTrak100 stopped pleasing us with the growing performance in case of 3 HDDs already, so that for 4, 5 and 6 HDDs the results remained unchanged.

In SequentialWrite pattern only 3ware controller proved dependent on the number of drives connected to it, having reached the top transfer rate of 78MB/sec for 4 HDDs configuration. On the diagram above you can clearly see that the graph consists of two parts: 1-2 HDDs and 3-4 HDDs. The graph changed its angle on the interval for 2-3 HDDs because at that moment the central DiskSwitch chip was shifting from work with one AccelerATA chip to work with two chips like that. DiskSwitch performance is no longer enough to work with each of the two AccelerATA chips with 100% efficiency. That is why the contribution to the overall performance made by each HDD separately appears somewhat lower. But nevertheless, the more HDDs get connected, the higher appears the speed.

Summing up the results for RAID 0 configuration, we can conclude that 3ware appeared an indisputable leader. Now let see if it retains the laurels in other RAID levels as well.