I’m trying to pick out a 32GB or, preferably, 64GB eMMC module for my board and I’m confused on how to select the right unit.
I see units out there with a single connector, but there are two connectors on the board. I assume this is for a single module with two connectors, but I could be wrong. Can I populate this thing with two eMMC modules? No, right?
If anyone could point me in the direction of a usable eMMC module model for the visionfive2 I would really appreciate it!
The Magus Gaius Mycelius, Jocundus
Only J9 is electrically relevant, J99 is for mechanical protection.
This should bring clarity:
Thank you for the info.
After reading this article, emmc and sdcards both:
- use non-volatile nand memory for storage
- offer very limited storage offerings max 128GB
- do not have as many data lanes as SSDs and Nvme’s. This implies they are slower than SSD’s and Nvme’s.
Nvme’s have more data lanes than SSD’s and may be accessed to read/write in parallel.
Older generation SSD’s may have more data lanes than sdcard/emmc, but they may only be accessed sequentially if I understood correctly.
To summarize I think that means nvme > ssd > emmc and sdcard, but please correct me or crystallize if I’m wrong.
Also specifically about the VF2, it only has one pcie lane to talk with. The implies the VF2 unfortunately cannot take advantage of all those nvme parallel capability read/write lanes. I’m not sure how that detail slipped by. I do hope the VF3 will not suffer from this shortcoming.
This is great info, thanks! I’m using a 1TB NVMe for my /home partition and an SD card, at present, with the debian release (with a custom updated kernel to add usbserial support) and I want to target the eMMC for developing my own os builds. The NVMe is noticeably more performant than the SD card, which is, of course, expected; even with the less than complete lane support you mention for VF2.
Fortunately eMMC will be plenty fast enough for my needs, and once I’m booting from it regularly my whole system should speed up a bit.
I went ahead and ordered the 128GB eMMC recommended in these threads. Excited to work with it!
This test dates back some time, but unfortunately I can’t take a more up-to-date measurement at the moment.
user@vfive2-8:~$ sudo hdparm --direct -t /dev/mmcblk0
Timing O_DIRECT disk reads: 14 MB in 4.05 seconds = 3.45 MB/sec
Allnet Plug on eMMC 5.1 storage media for Rock 4 /Rock E /Rock 3A /VisionFive2 64GB version
Note: I have two VisionFive2s, one with 4GB + 32GB eMMC, and another with 8GB + 64GB eMMC.
Got my eMMC module installed and formatted and used your test to compare them @SunWukong. Thanks for the tip!
The mmcblk1 is the SDcard off of which I am currently booted, and the mmcblk0 is the newly installed eMMC module.
gaiusjocundus@cyberdeck:~$ sudo hdparm --direct -t /dev/mmcblk1
Timing O_DIRECT disk reads: 64 MB in 3.01 seconds = 21.26 MB/sec
gaiusjocundus@cyberdeck:~$ sudo hdparm --direct -t /dev/mmcblk0
Timing O_DIRECT disk reads: 110 MB in 3.00 seconds = 36.66 MB/sec
Thanks everyone for your assistance and insights!
Update: Adding nvme results for those interested:
gaiusjocundus@cyberdeck:~$ sudo hdparm --direct -t /dev/nvme0n1
Timing O_DIRECT disk reads: 564 MB in 3.00 seconds = 187.99 MB/sec