SanDisk Professional G-DRIVE SSD and ArmorLock SSD Reviewby Ganesh T S on October 12, 2021 8:00 AM EST
Synthetic Benchmarks - ATTO and CrystalDiskMark
Benchmarks such as ATTO and CrystalDiskMark help provide a quick look at the performance of the direct-attached storage device. The results translate to the instantaneous performance numbers that consumers can expect for specific workloads, but do not account for changes in behavior when the unit is subject to long-term conditioning and/or thermal throttling. Yet another use of these synthetic benchmarks is the ability to gather information regarding support for specific storage device features that affect performance.
Western Digital claims speeds of up to 1000 MBps for the ArmorLock NVMe SSD and 1050 MBps for the G-DRIVE SSD. ATTO benchmarking is restricted to a single configuration in terms of queue depth, and is only representative of a small sub-set of real-world workloads. Interestingly, at QD4, the ArmorLock SSD hits 1.01GBps for both reads and writes, while the G-DRIVE SSD hits 1GBps+ only for reads. Writes top out at around 985 MBps. ATTO does allow the visualization of change in transfer rates as the I/O size changes, with optimal performance being reached around 512 KB for a queue depth of 4 for both SSDs.
CrystalDiskMark. for example, uses four different access traces for reads and writes over a configurable region size. Two of the traces are sequential accesses, while two are 4K random accesses. Internally, CrystalDiskMark uses the Microsoft DiskSpd storage testing tool. The 'Seq128K Q32T1' sequential traces use 128K block size with a queue depth of 32 from a single thread, while the '4K Q32T16' one does random 4K accesses with the same queue configuration, but from multiple threads. The 'Seq1M' traces use a 1MiB block size. The plain 'Rnd4K' one uses only a single queue and single thread . Comparing the '4K Q32T16' and '4K Q1T1' numbers can quickly tell us whether the storage device supports NCQ (native command queuing) / UASP (USB-attached SCSI protocol). If the numbers for the two access traces are in the same ballpark, NCQ / UASP is not supported. This assumes that the host port / drivers on the PC support UASP.
Both the ArmorLock SSD and G-DRIVE SSD exhibit similar sequential numbers - in fact, hitting more than the advertised 1050MBps numbers for both reads and writes under some specific workload constraints. The numbers also show UASP support. In the random accesses, the ArmorLock SSD with its internal SN700-class DRAM-equipped NVMe drive edges slightly ahead, compared to the SN550E-equipped G-DRIVE SSD. The significant change in the random read/write performance for different queue depths indicates that both units support native command queuing.