erkserkserks/Fast UTM shared directories using Samba.md

## Fast UTM shared directories using Samba.md

      
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              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.


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


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


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


Once the local account sambauser has been created, then add the corresponding samba user account:
sudo smbpasswd -a sambauser


Modify permissions of the shared directory so that sambauser can access it. For example:
chmod 770 ~/Downloads


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.


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>


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


Install cifs-utils so the samba share can be mounted:
sudo apt install cifs-utils


Create the mountpoint:
sudo mkdir /mnt/smb


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


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.


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