External USB SSD slow transfer speeds

[monkeyfella]

Hello

I have an external 8TB ssd disk, it's attached via USB and passthrough to a container.

I have been following this guide: https://pve.proxmox.com/wiki/Passthrough_Physical_Disk_to_Virtual_Machine_(VM)

My pve config has this line for the attachment of the disk to the VM:

scsi1: /dev/disk/by-id/ata-Samsung_SSD_870_QVO_8TB_S5SSNF0W404940V,discard=on,size=7814026584K,ssd=1

when I check lsusb on the host:

Bus 002 Device 002: ID 174c:235c ASMedia Technology Inc. Ugreen Storage Device
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

So it's connected to the high speed usb port, I have a qnap external raid enclosure attached to the same root hub, and those disks have no problems.

When I perform

dd if=/dev/zero of=/DATA/test1.img bs=1G count=1 oflag=dsync

to check the speed: I get
1073741824 bytes (1,1 GB, 1,0 GiB) copied, 7,9529 s, 135 MB/s

If I do the same test with the same disk on the host:
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 2.80608 s, 383 MB/s



And the problem is that as soon as I start to use the disk and read/write it slows down until it gets unresponsive. Sometimes the console is full of IO errors because of this.

How am I supposed to attach this harddrive properly so it get decent speeds?

I have the Minisforum MS-01

 

[m4ntic0r]

hm could not be a proxmox thing. i have the same 8TB SSD in an external case too, but using it with windows 11. and i see the ~130mb/s too, sometimes a little bit faster but far away from when the disk is attached to sata at the host.
i think its a special problem of this ssd in external cases.

its not the fastest drive and these speeds are normal is you are writing more than cache is there. thats by design. but on normal transfers you should see 400-500mb/s.

it looks like these external cases or controllers are ignoring the whole ssd cache. or the ssd recogniced this and is not using the cache

 

[_gabriel]

You just discover the QVO serie and in general QLC memory, which writes slower than HDD, and even poor while sustrain writes...

 

[m4ntic0r]

You just discover the QVO serie and in general QLC memory, which writes slower than HDD, and even poor while sustrain writes...

thats bullshit you cannot say that generally. the ssd is fast for the first 70-80gb written to it sequentially. then the speed will be slower. so dont make this nonsense.

i have multiple of these 8tb disk and they are only slow in external cases. on host you get 400-500mb/s until the cache is full.

 

[KrisFromFuture]

i've got 4TB Lexar NVME in 40GBps usb 4.0 case - and i got only 600MB/s instead 6000MB/s

any other possible solutions ?

 

[LnxBil]

In my experience, also the host USB controller has to be of high quality to get good speeds.