When you want to connect external storage to your PC, you usually have it easy: a pen drive if you don’t need a lot of capacity, or a USB hard drive if you have greater storage needs. However, when you are looking for the best performance, is a USB disk DAS , or a single external disk , a better choice? Let’s see it.
Of course, the simple option is an external disk, and generally users do not resort to devices such as DAS if we do not have large storage needs and, in addition, we want this to be fixed (since a DAS logically does not have the same portability as an external disk, and less than a pen drive). So is performance one of the advantages of DAS over USB hard drives?
DAS or USB hard drive, what gives better performance?
If we assume that a DAS is nothing more than an external hard drive, then the answer to the question is very simple: one does not matter. However, one of the advantages that DAS give us is precisely the possibility of combining several hard drives in a single volume, being able to configure it -depending on the DAS- in RAID configurations. In this case, if we talk about RAID0 and the DAS interface allows it, theoretically we would have twice the reading speed.
Take for example two units with a high level of sales. On the one hand, an external Seagate Expansion Desktop disk containing a 3.5 ″ 6 TB hard drive with a USB 3.0 interface, and on the other hand, a DAS TerraMaster D2-310 with capacity for two 2 hard drives. , 5 / 3.5 inches and with USB 3.1 interface.
The speed of the Seagate external hard drive is about 195 MB / s read and 190 MB / s write , while the theoretical maximum speed of the TerraMaster DAS is 401.7 MB / s read and 412.9 MB / s write ; As you can see with the naked eye, the speed offered by the DAS is double that of the hard disk, but this is for two reasons: on the one hand, due to the possibility of configuring a volume in RAID0 that doubles the speed, and on the other, because the DAS is USB 3.1 and we have compared it to a USB 3.0 hard drive.
If we change this DAS for the D5-300 model, which has 5 bays but the interface is USB 3.0, its maximum theoretical speeds become up to 215 MB / s read and 237 MB / s write . Here we see a slight increase in speed, but not enough to launch rockets, and you should also bear in mind that these speeds are the theoretical maximums and will always depend on the hard drive that we install in the DAS, as well as its brand and model.
So isn’t a DAS better?
DAS provides many advantages over an external USB hard drive, but performance is not the greatest of them. It is true that if the DAS controller is good, we can get the most out of the interface, something that normally does not happen with external hard drives, but really if you decide to buy a DAS instead of an external disk, it should be in order to have larger volume sizes and more versatility, forgoing mobility, not performance.
Yes it is true that when we talk about high workloads a DAS gives better results in terms of sustained performance, since as a general rule they have their own controller, something that relieves the load on the processor, and on the other hand they have a cooling system It maintains the disks installed in it at a better operating temperature, thus prolonging their useful life.
So, you should assess what interests you most when choosing one or the other option. A DAS is much more expensive, but it gives you greater possibilities in terms of capacity, greater versatility of use and yes, better performance. An external hard drive gives you greater mobility and is of course much cheaper than having to buy a DAS and its hard drives separately.
