Western Digital WD2500JB and its Serial ATA analogue are among the oldest Hard Disk drives participating in our shoot-out. They have no larger data buffer, no Native Command Queuing support, but nevertheless, they compete pretty successfully with their younger rivals. Showing no remarkable results in two pure modes (only reading or only writing), WD HDDs cope just fine with combined workloads demonstrating confident performance improvement as the percentage of write requests grows.

Modernized electronics of the WD2500JS improved lazy writing almost up to the level of the best competitors’ solutions. WD2500KS equipped with a larger buffer performs almost identically to WD2500JD.

Two server hard drives performed just like their desktop fellows, i.e. we didn’t notice any optimizations for specific types of workload. WD2500SB and WD2500JD graphs coincide and the results of WD2500SD are equal to those of WD2500JB. In other words, we can see three Western Digital firmware versions here with different read ahead algorithms and more enhanced lazy writing of WD2500JS. However, we cannot expect these 6 models to reveal any revolutionary performance differences.

So, let's sum up now.

Most of the existing HDDs do not offer efficient Native Command Queuing. Hitachi didn’t modify the look-ahead reading and deferred writing algorithms well enough, so NCQ lowers the drive’s performance in real applications. Seagate’s HDDs never had multi-threaded optimizations, so NCQ can only be useful in a limited number of tests with multiple competing requests for reading. Samsung’s NCQ implementation provokes many questions, too.

Maxtor was the only developer to do everything right, but then they stepped back for some reason. Perhaps a full-featured support of Native Command Queuing may lead to a loss of data in case of an emergency shutdown of the HDD, but the price of the changes in the newer models from Maxtor is too high. The only good news is that the speed of multi-threaded reading didn’t suffer and Maxtor’s HDDs do not lose anything in performance when NCQ is enabled.