What is USB Attached SCSI UASP & UAS Protocol

What is USB Attached SCSI (UAS) in Detail

USB is a cross-platform technology, which is keep updating from past 10 years. It helps for transferring and maintaining the backup of a large amount of files faster. Moreover, USB 3.0 currently supports speeds up to 5.0 Gbps of bidirectional bandwidth. Apart from knowing What is USB Attached SCSI, it is mainly a computer protocol that is used for moving the data to and from the different type of USB storage drives. Moreover, in the following section, we will discuss more UASP, its advantages, the difference between UAS and BOT and requirements for running UAS protocol.

About USB Attached SCSI

UAS is designed for USB SCSI Protocol. It is capable for faster read or writes data speeds to and from the storage devices such as hard disk drives, solid-state drives and also including the thumb drives. Moreover, UAS depends on USB protocol and utilizes the standard set of SCSI command.

Initially, UAS was a part of the USB 3.0 standard, but even it can be used also with the devices that comply with the slower USB 2.0 standard, just assuming the utilization of firmware, hardware, and the drivers, which are compatible with it. Generally, the use of UAS that provides faster data transfer as compared to the previous drivers i.e., USB Mass storage Bulk-only Transport (BOT). Moreover, UAS has been added in the latest USB 3.0 protocol standard, but, it may be used also at the USB 2.0 protocol speeds, with the assumption of compatible firmware, hardware etc. When it is being used with a solid state drive or SSD, then, this USB attached SCSI (UAS) becomes significantly faster than the Bulk-Only Transport protocol (BOT) for random reads and writes as well still, the speed would be lower than that of a native SATA 3 interface that is 6 Gbit/s.

Differentiate Between UAS and BOT

• UAS is really a new USB 3.0 protocol due to some reason replacing the earlier used USB 2.0 BOT protocol.
• Proposed a new USB 3.0 protocol, developer of UAS have presented two major changes in the architecture of it.

i. In previous command and query signals used to share common pipe along with transferred data. However, UAS doesn’t mix type of data transfer and each data type has a distinct pipe and not sharing with each other.

ii. Basically, UAS is multi-threaded, whereas BOT is a serial type (more or less) of the process.
iii. The last one is command query. Instead of BOT, the USB attached UAS or UASP SCSI the next-in-line signal.

Requirement for Running USB Attached SCSI

Clearly, understand that the USB attached UAS SCSI support easily turn on its need such as 4 platform-oriented elements for its functioning, which are as mentioned:

• The hardware device, which supports USB SCSI
• The firmware device that supports USB attached SCSI
  USB attached UAS SCSI is compatible inside the hard driver stack of the USB
• System controller that is compatible with the USB attached UAS SCSI

If any one out of 4 elements is missing then, the UAS will not be performing and USB 2.0 protocol of BOT would become, in this situation the backup mode to preserve or protect the compatibility.

Operating System Support

• Microsoft

Microsoft has added the native support for USB attached UAS SCSI to the new Windows 8 version. The drives have supported UAS load the “Uaspstor.sys” beside of the older one, “Usbstor.sys”. The Windows 8 supports USB attached SCSI or UAS by default over the USB 2.0 protocol as well. UAS drivers are certified by Microsoft by using Windows Hardware Certification Kit.

• Apple

Apple has added the native UAS support to the Operating System X 10.8, Mountain Lion. Here, in this, the drives utilizing the UAS show up as using the “IOUSBAttachedSCSI” instead of the earlier one, “IOUSBMassStorageClass kext”.

• Linux

As of the year 2012, the Linux kernel also gave the native support for UAS, but it had some kind of compatibility problems with Texas Instruments chipsets.

Advantages of USB attached SCSI

There are following points those are discussed below:

• The USB attached SCSI or UAS, which depends on USB protocol
• UAS makes utilization of standard command set of SCSI
• UAS provides faster transferring of data as compared to the earlier used USB device that was Mass Storage device Bulk-Only Transport drivers.

Conclusion

UAS is just a protocol and its main purpose is that its performance while reading or writing the data, becomes faster. Understanding the various aspects of UAS protocol, we have presented the entire information to let the users understand about what is USB attached SCSI UASP and its specification details. Also, we have discussed the difference between UAS and BOT, the requirement to run UAS and its advantages in detail. Also, we have mentioned the following platforms those are supported by USB attached UASP SCSI.