Poor external SSD performance

Please provide the following info (check/uncheck the boxes after creating this topic):
Software Version
DRIVE OS Linux 5.2.6
DRIVE OS Linux 5.2.6 and DriveWorks 4.0
DRIVE OS Linux 5.2.0
DRIVE OS Linux 5.2.0 and DriveWorks 3.5
NVIDIA DRIVE™ Software 10.0 (Linux)
NVIDIA DRIVE™ Software 9.0 (Linux)
other DRIVE OS version
other

Target Operating System
Linux
QNX
other

Hardware Platform
NVIDIA DRIVE™ AGX Xavier DevKit (E3550)
NVIDIA DRIVE™ AGX Pegasus DevKit (E3550)
other

I followed the steps in DriveWorks SDK Reference: High Throughput Recording but I have not had much success. The output of the dd command on the linked page is around 250MB/s whereas the same command when the SSD is connected to a laptop returns speeds of around 500MB/s. I have tried different SSDs and each one of them writes slower on the Pegasus than they do on a laptop. Each SSD is connected to the same caddy with the same cable, so the only difference I can see is the Pegasus. Is there something else to try? Is there a recommended approach to installing NVMe-based storage on the Pegasus using either the PCIe lanes or eSATA instead?

1 Like

Dear @jber4282,
Could you double check if ext4 file system is used on SSD and connected to usb3.0 port? Also, may I know the SSD details?

Hi @SivaRamaKrishnaNV

Yes, the SSD was formatted as ext4 and we have tried all available USB3.0 ports on the Pegasus. The SSD is a 2TB Samsung 870 EVO. We have also tried different cables and caddies and although they vary slightly, they still all perform better when connected to a laptop than the Pegasus.

Dear @jber4282,
Thanks for confirming. Could you share the dd command logs on both host and Xavier for our reference to know achieved BW?

Hi @SivaRamaKrishnaNV

Here are the logs:

Laptop:
jason@leatherman:~ $ dd if=/dev/zero of=/media/jason/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 8.84977 s, 607 MB/s
jason@leatherman:~ $ rm /media/jason/evo2tb/file
rm: remove regular file ‘/media/jason/evo2tb/file’? y
jason@leatherman:~ $ dd if=/dev/zero of=/media/jason/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 8.83981 s, 607 MB/s
jason@leatherman:~ $ rm /media/jason/evo2tb/file
rm: remove regular file ‘/media/jason/evo2tb/file’? y
jason@leatherman:~ $ dd if=/dev/zero of=/media/jason/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 8.85216 s, 606 MB/s

Pegasus:
nvidia@tegra-ubuntu:~$ dd if=/dev/zero of=/media/nvidia/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 16.8933 s, 318 MB/s
nvidia@tegra-ubuntu:~$ rm /media/nvidia/evo2tb/file
nvidia@tegra-ubuntu:~$ dd if=/dev/zero of=/media/nvidia/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 17.8918 s, 300 MB/s
nvidia@tegra-ubuntu:~$ rm /media/nvidia/evo2tb/file
nvidia@tegra-ubuntu:~$ dd if=/dev/zero of=/media/nvidia/evo2tb/file bs=1G count=5
5+0 records in
5+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 16.6518 s, 322 MB/s

Dear @jber4282,
You seems to be getting more than what is quoted in 870 EVO | Internal SSD | Specs & Features | Samsung Semiconductor Global ( sequencial R/W upto 530/560 MBps) which is strange. Please ensure using USB 3.x certified cable. But it seems using USB is better than eSATA.

Hi @SivaRamaKrishnaNV

Thanks for that info. We have a USB 3 certified cable. Nevertheless, this answer still doesn’t address why the same SSD is much slower on the Pegasus. We use the same cable for both tests. What do we have to change in the Pegasus’s configuration to get the best out of it? 322 MB/s is still much lower than what is quoted by Samsung.

Dear @jber4282,
Thank you for brining it to our attention. We have raised an bug ticket internnaly already about this issue. It will take some time to get the conclusion. I will update you once I hear from them.

Thanks @SivaRamaKrishnaNV