How to Improve USB 3.0 Speed in NAS on Proxmox and TrueNAS

Low SMB Access Speed to USB 3.0 Storage in TrueNAS on Proxmox

Low SMB access speed to USB 3.0 storage in TrueNAS on Proxmox is usually caused by several factors: incorrect USB controller configuration in the virtual machine, suboptimal SMB parameters, or insufficient performance of the USB connection itself. To achieve speeds of 150-180 MB/s, it is necessary to configure data transfer directly via PCIe, optimize SMB parameters, and ensure proper USB signal handling in the virtualized environment.

Contents

• Problem Analysis and Main Causes of Low Speed
• USB Controller Optimization in Proxmox VM
• SMB Configuration in TrueNAS for Maximum Performance
• Filesystem and Disk Pool Optimization
• Network Configuration and Performance
• Monitoring and Performance Diagnostics
• Practical Recommendations and Step-by-Step Instructions

Problem Analysis and Main Causes of Low Speed

Low SMB access speeds of 10-30 MB/s when expecting 150-180 MB/s indicate several possible issues in your configuration. Before moving to solutions, it’s important to understand the main causes of this performance degradation.

Main factors affecting USB 3.0 speed in a virtualized environment:

1. USB controller emulation - Proxmox uses standard USB emulation by default, which creates additional overhead
2. Lack of direct PCIe access - without passthrough, the USB controller works through a virtual layer
3. Incorrect SMB parameter configuration - default TrueNAS settings are not always optimal for high speeds
4. Filesystem issues - ZFS may not work optimally without proper caching configuration
5. Network limitations - even with good hardware, network settings can create bottlenecks

Important: Comparing performance between direct disk access in Windows (150-180 MB/s) and access through TrueNAS VM (10-30 MB/s) clearly shows that the problem lies in virtualization and settings, not in the hardware itself.

USB Controller Optimization in Proxmox VM

To achieve maximum USB 3.0 performance in a TrueNAS virtual machine, you need to properly configure the USB controller in Proxmox.

USB Passthrough Configuration

Step 1: Identify the USB Controller

lsusb -t

This command will show the USB device hierarchy. You need to find the root USB controller to which your external HDD enclosure is connected.

Step 2: Add USB Device to VM Configuration

Edit the TrueNAS virtual machine configuration file:

nano /etc/pve/qemu-server/100.conf  # 100 is your VM ID

Add the following lines to the device section:

args: -usbdevice hostbus=1,hostaddr=1

Or for more precise control:

args: -device usb-host,bus=usb-bus.0,hostbus=1,hostaddr=1

Step 3: Alternative Option with USB 3.0 xHCI Controller

If your host supports USB 3.0, use the xHCI controller:

args: -device usb-host,bus=ehci.0,hostbus=2,hostaddr=1

Additional Parameters for Performance Improvement

Add parameters to reduce latency:

args: -cpu host,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time

args: -machine pc,accel=kvm,usb=on

SMB Configuration in TrueNAS for Maximum Performance

After optimizing the USB controller, you need to properly configure the SMB service to achieve high data transfer speeds.

SMB Parameter Optimization

Step 1: Edit smb.conf

Open the SMB configuration file:

nano /usr/local/etc/smb4.conf

Add or modify the following parameters:

[global]
   server min protocol = SMB3
   server max protocol = SMB3_11
   client min protocol = SMB3
   client max protocol = SMB3_11
   deadtime = 15
   getwd cache = yes
   max connections = 1000
   preferred master = no
   local master = no
   domain master = no
   wins support = no
   aio read size = 16384
   aio write size = 16384
   use sendfile = yes
   write cache size = 16777216
   read raw = yes
   write raw = yes
   oplocks = yes
   level2 oplocks = yes
   strict locking = no
   max xmit = 65536
   name resolve order = bcast hosts
   socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=131072 SO_SNDBUF=131072

Step 2: Configure Specific Parameters for High Speeds

For USB 3.0 disks, add:

[global]
   smb2 leases = no
   lease directory = no
   inherit permissions = yes
   inherit acls = yes
   map archive = yes
   map hidden = yes
   map read only = yes
   store dos attributes = yes
   nt acl support = yes
   vfs objects = fruit streams
   fruit:metadata = stream
   fruit:model = MacSamba
   fruit:veto_appledouble = no
   fruit:posix_rename = yes
   fruit:zero_file_id = yes
   fruit:wipe_intentionally_left_blank_rfork = yes
   fruit:delete_empty_adfiles = yes

SMB Performance Optimization

Step 3: Configure Kernel Parameters

Add to /boot/loader.conf:

kern.ipc.somaxconn=32768
kern.maxfilesperproc=32768
kern.maxfiles=200000
net.inet.tcp.recvspace=65536
net.inet.tcp.sendspace=65536
net.inet.tcp.mssdflt=1460

Reboot the system to apply the settings.

Filesystem and Disk Pool Optimization

Proper ZFS and disk pool configuration is critical for achieving maximum USB 3.0 storage performance.

ZFS Pool Parameter Optimization

Step 1: Check Current Pool Settings

zpool get all storage_pool

Step 2: Optimize Settings for USB Disks

For USB 3.0 disks, the following parameters are recommended when creating a pool:

zpool create -o ashift=12 -o autotrim=on -o compression=lz4 -o feature@async_destroy=enabled -o feature@bookmarks=enabled -o feature@embedded_data=enabled -o feature@empty_dataobj=enabled -o feature@enabled_txg=enabled -o feature@extensible_dataset=enabled -o feature@filesystem_limits=enabled -o feature@hole_birth=enabled -o feature@large_blocks=enabled -o feature@lz4_compress=enabled -o feature@multi_vdev_crash_dump=enabled -o feature@spacemap_histogram=enabled -o feature=unsupported-raidz-expansion -o feature=unsupported-scrub-stats -o feature=unsupported-zpool-features -o feature=zpool_checkpoint storage_pool mirror /dev/da0 /dev/da1

For an existing pool:

zpool set ashift=12 storage_pool
zpool set autotrim=on storage_pool
zpool set compression=lz4 storage_pool

Caching and Buffer Optimization

Step 3: Configure ZFS Cache

# ARC cache size (optimal 50-70% of available RAM)
echo "kern.vm.vm_physmem_size=0" >> /boot/loader.conf
echo "vfs.zfs.arc_max=4G" >> /boot/loader.conf
echo "vfs.zfs.arc_min=512M" >> /boot/loader.conf

# Configure L2ARC (if you have SSD cache)
zpool add storage_pool cache /dev/ada0

Step 4: Optimize I/O Parameters

Add to /boot/loader.conf:

vfs.zfs.vdev.async_write_max_active=8
vfs.zfs.vdev.async_write_max_inflight=64
vfs.zfs.vdev.sync_write_max_active=10
vfs.zfs.vdev.sync_read_max_active=10
vfs.zfs.vdev.min_max_active=4
vfs.zfs.vdev.min_max_inflight=32
vfs.zfs.vdev.file_max_active=1
vfs.zfs.vdev.file_max_inflight=32

Network Configuration and Performance

Even with good hardware, incorrect network settings can significantly reduce SMB access performance.

Kernel Network Parameter Optimization

Step 1: Configure TCP Parameters

Add to /etc/sysctl.conf:

# TCP optimization
net.inet.tcp.delayed_ack=0
net.inet.tcp.recvspace=65536
net.inet.tcp.sendspace=65536
net.inet.tcp.mssdflt=1460
net.inet.tcp.window=65536
net.inet.tcp.nolocaltimewait=1

# Network buffers
kern.ipc.maxsockbuf=2097152
net.inet.tcp.sendbuf_max=2097152
net.inet.tcp.recvbuf_max=2097152

# SMB optimization
net.local.stream.recvspace=65536
net.local.stream.sendspace=65536

Apply the changes:

sysctl -f /etc/sysctl.conf

Network Adapter Configuration in VM

Step 2: Optimize Network Card in Proxmox

For TrueNAS VM, use the virtio network adapter with correct settings:

# In VM configuration
args: -device virtio-net-pci,netdev=vmnet0,mac=52:54:00:12:34:56

Step 3: Configure Jumbo Frames (if supported)

If all network hardware supports Jumbo Frames (9000 MTU):

# On TrueNAS
ifconfig igb0 mtu 9000

# On Proxmox host
ifconfig vmbr0 mtu 9000

Monitoring and Performance Diagnostics

To identify bottlenecks and optimize performance, it’s necessary to regularly monitor the system.

Monitoring Tools

Step 1: ZFS Performance Monitoring

# Current pool statistics
zpool iostat -l 1

# ARC cache statistics
vmstat -m

# SMB statistics
smbstatus -b

Step 2: Network Performance Analysis

# Monitor network activity
netstat -i

# Analyze TCP connections
tcpdump -i igb0 -n 'port 445'

# Test network speed
iperf3 -c server_IP

Step 3: Performance Logging

Enable extended logging for diagnostics:

# In smb.conf
[global]
   log level = 2
   syslog = 2

# In syslog.conf
local0.*                                                /var/log/samba.log

Practical Recommendations and Step-by-Step Instructions

Comprehensive Optimization Plan

Step 1: Check Basic Configuration

1. Ensure USB disks are properly identified in TrueNAS:

   bash

   camcontrol devlist
   

2. Check pool status:

   bash

   zpool status
   zpool list
   

3. Test speed directly through ZFS:

   bash

   dd if=/dev/zero of=/mnt/storage_pool/testfile bs=1M count=1024 oflag=direct
   

Step 2: Optimize USB Controller

1. Identify the exact USB controller:

   bash

   usbconfig dump_all_desc
   

2. Configure passthrough in Proxmox VM configuration:

   args: -device usb-host,bus=usb-bus.0,hostbus=1,hostaddr=1
   

3. Reboot the VM and check disk availability.

Step 3: Optimize SMB and Network

1. Apply the optimized smb.conf
2. Configure kernel parameters in sysctl.conf
3. Check network settings and enable Jumbo Frames if necessary
4. Reboot the system to apply all changes

Step 4: Performance Testing

Use the following commands for testing:

# Read speed test
dd if=/mnt/storage_pool/testfile of=/dev/null bs=1M count=1024 iflag=direct

# Write speed test
dd if=/dev/zero of=/mnt/storage_pool/testfile bs=1M count=1024 oflag=direct

# Test via SMB
smbclient //nas_ip/share -U username -c "get testfile /tmp/testfile"

Expected Results

After proper configuration, you should achieve the following metrics:

• Read/write through ZFS: 120-160 MB/s
• SMB access: 100-140 MB/s
• Latency: < 5ms for small files
• Throughput: > 90% of USB 3.0 theoretical maximum

Possible Issues and Solutions

1. If speed remains low:

   • Check the USB cable (use a short, high-quality cable)
   • Ensure disks are working in UASP mode
   • Try a different USB port (preferably rear on the motherboard)

2. If there are SMB errors:

   • Check logs: tail -f /var/log/samba.log
   • Ensure antivirus is not blocking access
   • Check file access permissions

3. If the system is unstable:

   • Reduce ARC cache size
   • Disable unnecessary SMB features
   • Check disk temperatures

Conclusion

To achieve maximum USB 3.0 speed in your Proxmox + TrueNAS configuration, you need to take a comprehensive approach to optimizing several components:

1. Configure USB passthrough in Proxmox for direct controller access
2. Optimize SMB parameters with advanced settings for high speeds
3. Configure ZFS pool with correct parameters for USB disks
4. Optimize the network considering SMB protocol specifics
5. Regularly monitor performance to identify bottlenecks

With proper configuration, you can achieve SMB speeds of 100-140 MB/s, which corresponds to expected metrics for USB 3.0 connection. The key factor is ensuring direct access to USB hardware without emulation, which allows avoiding significant overhead in the virtualized environment.

Sources

1. TrueNAS SMB Performance Optimization Guide
2. Proxmox USB Passthrough Configuration
3. ZFS Performance Tuning for USB Storage
4. SMB3 Protocol Optimization Guide
5. FreeBSD USB 3.0 Performance Best Practices
6. Network Optimization for High-Speed Storage