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  • rpg1966 - Tuesday, July 10, 2018 - link

    Why are random read speeds always so much lower than sequential read speeds, even with solid state devices? As someone who doesn't know the nuts and bolts of what goes under the covers, it seems that that for a solid state device, random access wouldn't be appreciably slower than sequential access.
  • jordanclock - Tuesday, July 10, 2018 - link

    There is still overhead in reading different parts of a solid state drive, it's just much lower. For instance, if the reads are sequential, it's easy for the controller to 'predict' which data will be requested next and already start the read.
  • Billy Tallis - Tuesday, July 10, 2018 - link

    Sequential transfers usually involve larger chunks of data than random I/O. Generally, random I/O speeds are quoted for 4kB transfers, while sequential I/O is usually measured with 128kB transfers, so there are 32 times fewer commands for the drive to process when handling sequential I/O. Internally, flash memory now usually also has a page size that is larger than 4kB, so you can perform 8kB or 16kB reads in almost the same amount of time as a 4kB read, but that only helps sequential access.
  • thrawn3 - Tuesday, July 10, 2018 - link

    Can the external drive fall back to USB 3.0 if plugged into a non thunderbolt port? That is the key feature I keep looking for is Thunderbolt with fallback even if it requires adding in an extra power supply in the mix.
  • repoman27 - Tuesday, July 10, 2018 - link

    No, as stated in the article: “The port is enabled by the Intel DSL6340 Thunderbolt 3 Controller - note that this belongs to the Alpine Ridge family, and hence, works only with Thunderbolt 3 Type-C ports.”

    The JHL7440 Titan Ridge controller will allow optional compatibility of a device’s upstream facing port with USB 2.0/3.x hosts. However, it still won’t be able to bridge PCIe only devices (such as an NVMe SSD) to USB.
  • thrawn3 - Tuesday, July 10, 2018 - link

    My fault for missing that in the article.

    Really sad but I guess expected. I know it is fundamentally possible as shown by the announced but not yet on sale ASM2362 and JMS583 controllers shown at Computex that will bridge NVME/PCIe to USB 3.1. I guess just more waiting for a real solution that has full function on Thunderbolt and still works at a degraded level on USB.

    Biggest reason I have run into a few times already is upgrading the SSDs in clients laptops by cloning to new larger drives is worlds easier if one of them can be attached externally.
  • thrawn3 - Tuesday, July 10, 2018 - link

    I can't/won't put a link to it but I just did a search for the JMicron controller and found a device listed as using it direct ship from China. No clue if it works at all but I'll probably get one once they are selling from local companies rather than overseas shipping.
  • Joffer - Tuesday, July 10, 2018 - link

    Just search for "JMS583" on AliExpress.com and you'll find 5 devices :) I'm ordering one for sure
  • repoman27 - Tuesday, July 10, 2018 - link

    Oh, hey, that would do the trick. Strong work, JMicron. So on it’s own it would allow NVMe drives to connect to either USB or Thunderbolt 3 ports at up to SuperSpeed USB 10 Gbps signaling rates. Or it could be paired with the Intel JHL7440 Thunderbolt 3 controller to make a device that supports both USB and Thunderbolt hosts natively.
  • HStewart - Tuesday, July 10, 2018 - link

    I think we have to wait for Titan Ridge for this - I would be curious comparing this portable drive to one using controller mention. For one thing TB3 has a faster rate and I believe it works better with more device connected on it then USB 3.1

    Since Intel has basically open the Specifications on TB3 since especially Apple exclusivity is over with - I even expect one day we TB3 controllers from other then Intel.

    But I don't think it matters that much especially if you have laptop with both TB3 and normal USB-c like my dell XPS 2in1 ( and 15 has two TB3 ) - only bad thing is that drive enclosure will not work on normal USB-c port if that is only thing available.
  • PeachNCream - Tuesday, July 10, 2018 - link

    That's some nice performance over Thunderbolt! NAND's powered off data retention still worries me a bit though so certain scenarios where an external storage device is used only infrequently and encounters data corruption as a result worries me (even moreso now with QLC on the horizon).
  • stuffwhy - Tuesday, July 10, 2018 - link

    Noticing a reference to "works only with Thunderbolt 3 Type-C ports" does this mean that it has no back compatibility with Thunderbolt 2/1 ports?
  • nagi603 - Wednesday, July 11, 2018 - link

    I wish there was a low-cost option for just debugging an NVMe-based system.... :-/
  • TiTi - Sunday, July 22, 2018 - link

    What is the impact on the performance of the Thunderbolt controler?
    Could you compare the SanDisk SSD with Tekq Rapide vs installed on the motherboard?

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