Intel IOMeter: Sequential Write

Now we are passing over to the writes:

Just like in the previous case we will consider the results of 80GB HDDs first.

Promise SATA 150 TX2 Plus controller proved also very fast when processing write requests (in WB mode). But the SiliconImage controller is also evidently faster than Promise ATA controller. Have you noticed that the graph for SATA Promise controller in WB mode is always about one step ahead of the SiliconImage graph (I still insist on the assumption that Promise combines data packs :) Even the angle of inclination on the same intervals is similar!

Note that a stumbling stone for SiliconImage controller appeared 8KB data blocks.

The performance of 120GB HDDs gave us to understand that larger cache-buffer is of no effect during sequential writes. Anyway, why did we expect it to speed up the writes at all? If the amount of sequential data written onto the hard disk drive is much larger than the buffer size, then the latter will have absolutely no influence on the write speed (unlike the way HDTach works). Also take note that ST3120024A HDD (Barracuda ATA V with 8MB cache-buffer) processed writes slower than ST3120023A (Barracuda ATA V with 2MB cache-buffer). In other words, it looks as if the large buffer has negatively affected the HDD performance, doesn’t it? Well, I assume that it is mostly not because of the buffer size increase but because of the different firmware version of the HDD with 8MB cache-buffer.

And in conclusion let’s check the CPU utilization during writes:

As we have expected, the situation is about the same as we saw in case of reads. When we process smaller data blocks, the CPU utilization for Promise SATA 150 TX2 Plus controller reaches 100% in WB mode and hardly overcomes 50% in WT mode. SiliconImage controller loads the CPU a little bit more than Promise SATA 150 TX2 Plus in WT mode. But the best results were again demonstrated by the good old Promise Ultra100 TX2 buddy.