Performance

USB 2.0

A Seagate 7200.7 8MB cache 7200RPM drive was used for our performance tests.


The USB interface is quite constant up to around 140GB on this hard drive with around 32MB/s. After that the transfer dips and stays just above 30MB/s


This image shows how the hard drive behaves when hooked up directly to the IDE channel (blue) compared to the USB speed achieved (red). As you can see, there is a tiny dip toward the end when connected to USB is limited by the slow outer read speed of the Seagate drive. The CPU utilization of 8% is a bit high for such an enclosure.


The ATTO benchmark gives us quite similar results. Write speeds with USB 2.0 are just above 33MB/s while read speed max out at just over 26MB/s.

LAN

The transfer speed over the Ethernet connection is a very good and constant 10.6MB/s. The CPU utilization rises to 15% which is quite high, for a simple operation of moving data.


The ATTO benchmark gives us very similar results once again, but read speeds are constantly larger compared to the writing speed. Still this result is quite good.

RAID

RAID 1

Two or more enclosures, to a maximum of 8 can be bound together by using the "NDAS Bind Manager" Software. At first, both drives appear as single drives. They can be bound by selecting them and then selecting the type of binding (RAID 0 or RAID 1). To successfully bind drives, they need to be unmounted in windows and then remounted and formatted once bound.


The two enclosures were first bound as RAID 1. This means that all the data available on one drive is mirrored on the other. If one of the two drives fail, the user does not lose the data, as there is still one healthy drive available.


Naturally, the read speed of RAID 1 remains very close to that of a single drive, as there is no extra workload on the RAID array when reading from it.


The ATTO benchmark also shows similar read speeds of just under 10MB/s, but the write speed maxes out at just under 4MB/s. This was to be expected, as all the data needs to be mirrored.

RAID 0

Next, the drives were bound in RAID 0. This should increase read speeds as both drives are written on at the same time and can be read from at the same time. This means that both drives show up as one large drive in Windows. If one fails, all data on both drives is lost.


Here we find something interesting. First selecting a start size of 0.5KB is not possible anymore, the smallest size possible is 1KB. While the RAID array has some great performance, with read speeds climbing fast up to 64KB block size. After that the read speed shows up as a mere 0.3MB/s. The write speeds have not changed much when compared to a single drive. Needless to say, the RAID array reached the same read speeds of a single Ethernet based drive at a block size of 32KB.

Testing the drive with any other tool beside normal HDD benchmark tools is not possible, due to the NDAS software. The drive shows as a normal Windows drive, thus there is no way to use IPs or networked drives to test the bandwidth.