Fast UTM shared directories using Samba

Fast UTM shared directories using Samba.md

Fast UTM shared directories using Samba

Problem

UTM's shared directory implementation relies on SPICE WebDAV, which is slow.

Solution

Use Samba for faster shared directories. Samba is ~5x faster, see benchmarks at the end.

Mac Setup

Note: Tested on macOS 11.4 on M1 Macbook Air, UTM 2.1.1, Ubuntu 20.04 arm64.

1. Install samba using MacPorts. The built in macOS samba may work, but I have not tested this. The macOS version of samba is non-standard and is more difficult to find documentation for.

   sudo port install samba4
   

2. Create the samba configuration file

   sudo vi /opt/local/etc/samba/smb.conf
   

   Here is an example configuration that shares the ~/Downloads directory on the lo0 (loopback) interface for the sambauser user. Note that the samba server only listens on the loopback interface; it is inaccessible outside of the local machine.

   [global]
      workgroup = WORKGROUP 
      server string = samba server
      server role = standalone server
      bind interfaces only = yes
      interfaces = lo0
      max log size = 50
      passdb backend = tdbsam
   
   [Downloads]
      comment = Downloads 
      path = /Users/<username>/Downloads
      valid users = sambauser
      create mask = 664
      public = no
      writable = yes
   

   You may also need to create the samba log directory: sudo mkdir -p /opt/local/var/log/samba

3. In macOS preferences, create a new (sharing only) user called sambauser.

4. Once the local account sambauser has been created, then add the corresponding samba user account:

   sudo smbpasswd -a sambauser
   

5. Modify permissions of the shared directory so that sambauser can access it. For example:

   chmod 770 ~/Downloads
   

6. Test authentication (run both commands on macOS):

   Run the server:

   sudo /opt/local/sbin/smbd  --debuglevel=10 --log-stdout --foreground
   

   Connect to the server:

   smbclient -L localhost -U sambauser
   

   You should be able to authenticate successfully.

7. Configure macOS to launch samba server at boot.

   Create the launchd plist:

   sudo vi /Library/LaunchDaemons/org.samba.smbd.plist
   

   Add the following:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
   <plist version="1.0">
   	<dict>
   		<key>Label</key>
   		<string>org.samba.smbd</string>
   		<key>ProgramArguments</key>
   		<array>
   			<string>/opt/local/sbin/smbd</string>
   			<string>--foreground</string>
   			<string>--no-process-group</string>
   		</array>
   		<key>RunAtLoad</key>
   		<true/>
   		<key>KeepAlive</key>
   		<true/>
   		<key>ServiceDescription</key>
   		<string>samba</string>
   	</dict>
   </plist>
   

8. Load and start the job

   Run:

   sudo launchctl load /Library/LaunchDaemons/org.samba.smbd.plist
   

   You should see success in the logs:

   tail -f /opt/local/var/log/samba/log.smbd
   

   
   [2021/06/18 18:20:19.580395,  0] ../../source3/smbd/server.c:1784(main)
     smbd version 4.13.1 started.
     Copyright Andrew Tridgell and the Samba Team 1992-2020
   [2021/06/18 18:20:19.593845,  0] ../../lib/util/become_daemon.c:136(daemon_ready)
     daemon_ready: daemon 'smbd' finished starting up and ready to serve connections
   

   You should see smbd processes when running ps:

   ps aux | grep smbd
   

   root              4619   0.0  0.1  4790608   9632   ??  S     6:20PM   0:00.01 /opt/local/sbin/smbd --foreground --no-process-group
   root              4616   0.0  0.0  4792928   4880   ??  S     6:20PM   0:00.00 /opt/local/sbin/smbd --foreground --no-process-group
   root              4615   0.0  0.0  4758640   3216   ??  S     6:20PM   0:00.00 /opt/local/sbin/smbd --foreground --no-process-group
   root              4614   0.0  0.0  4766832   3664   ??  S     6:20PM   0:00.00 /opt/local/sbin/smbd --foreground --no-process-group
   root              4613   0.0  0.1 408484096  18016   ??  Ss    6:20PM   0:00.07 /opt/local/sbin/smbd --foreground --no-process-group
   

   Reboot your mac and check that smbd is runnning.

Ubuntu Setup

1. Install cifs-utils so the samba share can be mounted:

   sudo apt install cifs-utils
   

2. Create the mountpoint:

   sudo mkdir /mnt/smb
   

3. Mount the samba share. Note: With the default UTM/QEMU configuration, the guest can access the host at 10.0.2.2.

   sudo mount -t cifs -o user=sambauser /10.0.2.2/Downloads /mnt/smb
   

4. Mount smb share automatically at boot.

   Create credential file:

   vi /home/<username>/.smbcredentials
   

   Add the following:

   username=sambauser
   password=<your password here>
   

   Open fstab file:

   sudo vi /etc/fstab
   

   Add the following:

   //10.0.2.2/Downloads /mnt/smb cifs uid=1000,credentials=/home/<username>/.smbcredentials 0 0
   

   You can find your uid by running id -u.

   Test by running:

   sudo mount -a
   

   No errors should appear.

5. Reboot the Ubuntu VM and check that /mnt/smb has the expected contents.

Benchmarks

Benchmarks show that Samba is significantly (~5x) faster than WebDAV.

The below command creates a 4GB file and performs 4KB reads and writes using a 75%/25% split within the file, with 64 operations running at a time (source):

fio --randrepeat=1 --ioengine=libaio --direct=1 --gtod_reduce=1 --name=test --bs=4k --iodepth=64 --readwrite=randrw --rwmixread=75 --size=4G --filename=/mnt/smb/testfile

WebDAV Results

test: (groupid=0, jobs=1): err= 0: pid=4104: Sat Jun 19 04:45:23 2021
  read: IOPS=4174, BW=16.3MiB/s (17.1MB/s)(3070MiB/188281msec)
   bw (  KiB/s): min=  386, max=24769, per=100.00%, avg=18492.86, stdev=4240.84, samples=328
   iops        : min=   96, max= 6192, avg=4622.96, stdev=1060.22, samples=328
  write: IOPS=1395, BW=5580KiB/s (5714kB/s)(1026MiB/188281msec); 0 zone resets
   bw (  KiB/s): min=  111, max= 8784, per=100.00%, avg=6183.13, stdev=1437.66, samples=328
   iops        : min=   27, max= 2196, avg=1545.49, stdev=359.40, samples=328
  cpu          : usr=2.07%, sys=12.78%, ctx=1048728, majf=1, minf=126
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
     issued rwts: total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=64

Run status group 0 (all jobs):
   READ: bw=16.3MiB/s (17.1MB/s), 16.3MiB/s-16.3MiB/s (17.1MB/s-17.1MB/s), io=3070MiB (3219MB), run=188281-188281msec
  WRITE: bw=5580KiB/s (5714kB/s), 5580KiB/s-5580KiB/s (5714kB/s-5714kB/s), io=1026MiB (1076MB), run=188281-188281msec

Samba Results

test: (groupid=0, jobs=1): err= 0: pid=4135: Sat Jun 19 04:51:19 2021
  read: IOPS=20.4k, BW=79.6MiB/s (83.5MB/s)(3070MiB/38572msec)
   bw (  KiB/s): min=63480, max=119361, per=99.77%, avg=81313.23, stdev=10849.17, samples=77
   iops        : min=15870, max=29840, avg=20328.09, stdev=2712.31, samples=77
  write: IOPS=6809, BW=26.6MiB/s (27.9MB/s)(1026MiB/38572msec); 0 zone resets
   bw (  KiB/s): min=21880, max=40088, per=99.77%, avg=27175.34, stdev=3643.98, samples=77
   iops        : min= 5470, max=10022, avg=6793.61, stdev=911.01, samples=77
  cpu          : usr=5.23%, sys=57.15%, ctx=204667, majf=0, minf=16
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
     issued rwts: total=785920,262656,0,0 short=0,0,0,0 dropped=0,0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=64

Run status group 0 (all jobs):
   READ: bw=79.6MiB/s (83.5MB/s), 79.6MiB/s-79.6MiB/s (83.5MB/s-83.5MB/s), io=3070MiB (3219MB), run=38572-38572msec
  WRITE: bw=26.6MiB/s (27.9MB/s), 26.6MiB/s-26.6MiB/s (27.9MB/s-27.9MB/s), io=1026MiB (1076MB), run=38572-38572msec

Hi there, I switched over to "Shared Network" in UTM and thankfully got some reasonable looking throughput:

Run status group 0 (all jobs):
   READ: bw=104MiB/s (109MB/s), 104MiB/s-104MiB/s (109MB/s-109MB/s), io=3070MiB (3219MB), run=29516-29516msec
  WRITE: bw=34.8MiB/s (36.4MB/s), 34.8MiB/s-34.8MiB/s (36.4MB/s-36.4MB/s), io=1026MiB (1076MB), run=29516-29516msec

CPU utilization on the M1 Max was through the roof though, and the raw performance seen here is nothing to write home about especially considering this is local machine to local machine, and that 2.5Gbit ethernet is already way faster (even my Wifi is faster than this write speed), but... I'll take what I can get if this is the best we can do for now.

Also, Emulated VLAN was not good. I could curl google.com, but any time I pinged anything it reported lots of errors. Seemed to be pretty buggy. And yeah, could confirm, in that mode I couldn't even connect to smb.

Hi! I followed through the guideline successfully till the moment of actually working with the shares (accessing them is possible), but they appear all empty except for the directories: See https://apple.stackexchange.com/questions/466771/smbd-on-macos-shares-appear-empty-only-directories-no-files. Anyone experienced the same? Any hints?

I have been trying to install samba but unfortunatley it does not work.
I am running Samba 4.22.1
On OSX15

If i enter this string sudo launchctl load /Library/LaunchDaemons/org.samba.smbd.plist
I get the following error. Invalid option --log-stdout: unknown option

If I enter this smbclient -L localhost -U sambauser

I get this error INTERNAL ERROR: Signal 6: Abort trap: 6 in smbclient () () pid 2604 (4.22.1)