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 claims read and write speeds of around 2 GBps for the SanDisk Extreme PRO Portable SSD v2, while Crucial claims speeds of 800 MBps for the X6. Both of these are backed up by the ATTO benchmarks provided below. 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. It 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 in the SanDisk model, and around 128KB for the X6.

ATTO Benchmarks

The ATTO read numbers for the X6 were a bit off, despite repeated retries. As the rest of the benchmarks show, the X6 is only able to reach advertised numbers for real-world workloads.

CrystalDiskMark 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.

CrystalDiskMark Benchmarks

The ability of the SanDisk Extreme PRO to support the NCQ / UASP features was never in question. The X6 with its native flash controller is the more interesting product in this case, and we see that it does support the features essential for SSD-like performance.

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  • arashi - Friday, August 20, 2021 - link

    That's for the 4TB one, but for the 1TB variant it's still 200GB, which is plenty big. Reply
  • repoman27 - Thursday, August 19, 2021 - link

    @ganeshts why aren’t the results from your recent review of the Silverstone MS12 and Yottamaster HC2-C3 USB 3.2 Gen 2x2 20Gbps enclosures included in these charts?

    I’d be very interested to see how a roll your own solution with SK hynix Gold P31 fares against the SanDisk Extreme V2 and Extreme PRO V2. This would be especially useful at the 2TB capacity level, as WD seems to be charging a $100 premium for the 4TB models, and the Gold P31 maxes out at 2TB now.
  • ganeshts - Thursday, August 19, 2021 - link

    Yes, valid question. I thought about it a bit while preparing the graphs, and finally felt that the gulf in the capacity points (1TB vs. 4TB) could lead to readers misunderstanding the relative merits of the two platforms. So, decided to focus on the 'high-capacity' aspect alone.

    I do have the review of the Seagate FireCuda Gaming SSD (20Gbps) 1TB coming up soon, will be including the storage bridge results in that for comparison.

    As you mention, 2TB is fast becoming the mainstream offering in terms of capacity as 3D NAND layer counts keep going up. I will try to add the new testbed results from the old 2TB samples in future reviews.
  • flgt - Thursday, August 19, 2021 - link

    I’ve been really happy with my 2TB SanDisk. It breathed new life into my Xbox One X when I realized I’d be stuck with it for the foreseeable future. Reply
  • COtech - Thursday, August 19, 2021 - link

    How often do these portable SSDs need to be powered to reliably retain data ?

    Are they a good archive solution?
  • Tams80 - Thursday, August 19, 2021 - link

    Unless you're moving them at lot (or will take them on a rough journey), then I think it's a toss-up.

    As always, redundancy is important and for that Blu-ray archival disks are a great choice as one of the back-ups.
  • data21 - Tuesday, September 14, 2021 - link

    Nicely written blog on SanDisk Extreme PRO and Crucial X6 4TB Portable SSDs comparisions. for data recovery related issued in SSD can reach out to lifeguard data recovery services Reply
  • jabakobob - Wednesday, November 3, 2021 - link

    I'd like to correct a major error in this review: The X6 does not have 800GB of SLC cache.

    Instead, it just uses empty QLC cells as cache and writes only 1 bit to them instead of 4. So it effectively has a big SLC cache as long as it is <20% full. But the fuller it gets, the less cache it has!

    So basically it's a nice and fast drive as long as you only use 800GB. If you use more than that, performance craters.

    If you buy this drive to store a lot of data, it will never perform as well as in the tests. I assume most of the tests (except the worst case test) were done with an empty drive, so they are pretty much useless. It would be interesting how the drive would perform if it is 50% full or 80% full.

    If you actually need 4TB of capacity, don't buy this drive.

  • chemist1 - Friday, August 26, 2022 - link

    In order to make these tests as real-world as possible, you should first add files to the disks until they are about 50%-60% full (as opposed to running them on empty disks). Do you do that? Reply
  • yifu - Monday, October 10, 2022 - link

    I bought the x6 2tb last month, a return item for 110€. Some 500gb write on disk.
    I loved it. It Use very little power. I don’t think you test on the new firmware. Plugged in iPad Pro all day forgot to unplug. Didn’t even use 1% of batterie. I guess host device sleep, x6 drove no power. Great product for its targeted users environment.

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