• Source server is a Windows 2019 VM on Hyper-V with 4 mail data storage disks attached (D, E, F, G)
• Linux test server is a Ubuntu 24.04 VM hosted on our proxmox cluster
• For the data replication I've used a network share we created on one of our full NVMe SAN/SAN (Huawei dorado 5000), exported with both NFS and CIFS.

• On existing SM windows server, via CIFS, (mapped as letter Z: for later use with robocopy)
• On the test Linux VM via NFS (as /mnt/mail_data). /etc/fstab entry on the Lifor it looks like this:

filer03:/mail_data  /mnt/mail_data  nfs     rw,fsc,async,ac,actimeo=300,noatime,nconnect=16,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys 0 0

• Installed unbound as local DNS resolver
• Installed SmarterMail Linux BETA (without web server) and configured basic stuff (bindings, dns set to local unbound resolver and other general settings)
• Installed caddy web server (for reverse proxy with automatic HTTPS certificates handling). /etc/caddy/Caddyfile content looks like this:

{
        admin 127.0.0.1:2019
        grace_period 3s
        log {
                output file /var/log/caddy/caddy.log {
                        roll_size 250MiB
                        roll_keep_for 15d
                }
                level ERROR
        }
        email letsencrypt@swisscenter.com
        on_demand_tls {
                ask http://127.0.0.1:5000/ask
                interval 2m
                burst 10000
        }
        default_sni mail03.swisscenter.com
}

(common) {
        # Return server FQDN
        @sc_server_fqdn {
                path /_sc_get_server_fqdn
        }
        respond @sc_server_fqdn "mail03.swisscenter.com" 200 {
                close
        }

        # Reverse proxy the request to SmarterMail endpoint
        reverse_proxy http://127.0.0.1:17017
}

(ondemand) {
        tls {
                on_demand
        }
}

# Host related endpoints
https://localhost, https://localhost.localdomain {
        tls internal
}

# Main host
mail03.swisscenter.com {
        import common
}
http:// {
        import common
}
https:// {
        import ondemand
        import common
}

• Checked that SmarterMail on the Linux VM is running and the web interface is answering through it's public IP bound to the caddy webserver.
• Logged in as admin and disabled all retrieval services (IMAP, POP, EWS) to avoid importing any external stuff to this server.
• Stopped the SmarterMail server on the linux host
• Replaced /etc/smartermail/administrators.json with the one from source server
• Exported anti-spam rules from source server and re-imported them in destination server
• Copied current domains config-only files (well mostly all but without stats, indexing and GRP files)

robocopy "D:\SmarterMail\Domains\*" "Z:\domains" /E /R:1 /W:1 /XF *.stat* *.grp /XD FileStore IndexV2 /NP /LOG+:"%TEMP%\RoboCopy.log"
robocopy "E:\SmarterMail\Domains\*" "Z:\domains" /E /R:1 /W:1 /XF *.stat* *.grp /XD FileStore IndexV2 /NP /LOG+:"%TEMP%\RoboCopy.log"
robocopy "F:\SmarterMail\Domains\*" "Z:\domains" /E /R:1 /W:1 /XF *.stat* *.grp /XD FileStore IndexV2 /NP /LOG+:"%TEMP%\RoboCopy.log"
robocopy "G:\SmarterMail\Domains\*" "Z:\domains" /E /R:1 /W:1 /XF *.stat* *.grp /XD FileStore IndexV2 /NP /LOG+:"%TEMP%\RoboCopy.log"

• Replaced /etc/smartermail/domains.json with the one from source server and replaced the domain paths with a sed oneliner:

sed -i 's/[DEFG]\:\\\\smartermail\\\\domains\\\\/\/mnt\/mail_data\/domains\//ig' domains.json

• Started SmarterMail again on the Linux host and connected to the web interface.
• At this point it started converting attached domains, probably to update some path and stuff (so they are compatible with Linux paths ?)
• After a few minutes the login screen appeared and I was able to log-in and list the domains, log into some user accounts, etc. Seems quite a success so far.

[2024.06.14] 03:56:09.810 [domain1.com] Could not find '/mnt/mail_data/domains/domain1.com/Archived Data/settings.json' this domain will now be converted.
[2024.06.14] 03:56:09.813 [domain1.com] Conversion started.
[2024.06.14] 03:56:09.817 [domain1.com][Error] Message: Unable to read important domain data file
[2024.06.14] Exception: SmarterMail.Standard.Files.Exceptions.SMNotFoundException: Could not find a part of the path '/mnt/mail_data/domains/domain1.com'.
[2024.06.14]  ---> System.IO.DirectoryNotFoundException: Could not find a part of the path '/mnt/mail_data/domains/domain1.com'.
[2024.06.14]    at System.IO.Enumeration.FileSystemEnumerator`1.Init()
[2024.06.14]    at System.IO.Enumeration.FileSystemEnumerable`1..ctor(String directory, FindTransform transform, EnumerationOptions options, Boolean isNormalized)
[2024.06.14]    at System.IO.Enumeration.FileSystemEnumerableFactory.UserFiles(String directory, String expression, EnumerationOptions options)
[2024.06.14]    at System.IO.Directory.InternalEnumeratePaths(String path, String searchPattern, SearchTarget searchTarget, EnumerationOptions options)
[2024.06.14]    at System.IO.Directory.GetFiles(String path, String searchPattern, EnumerationOptions enumerationOptions)
[2024.06.14]    at SmarterMail.Standard.Files.DirectoryX.GetFiles(String path) in /build/SmarterMail/gitsrc/src/SmarterMail.Standard/Files/DirectoryX.cs:line 207
[2024.06.14]    --- End of inner exception stack trace ---
[2024.06.14]    at SmarterMail.Standard.Files.DirectoryX.GetFiles(String path) in /build/SmarterMail/gitsrc/src/SmarterMail.Standard/Files/DirectoryX.cs:line 218
[2024.06.14]    at SmarterMail.Data.Converters.DomainConverter.ReadSourceFiles() in /build/SmarterMail/gitsrc/src/SmarterMail/MailService/Data/Converters/DomainConverter.cs:line 534
[2024.06.14]    at SmarterMail.Data.Converters.DomainConverter.Convert(String domainPath, String domain, UpgradeStatus status) in /build/SmarterMail/gitsrc/src/SmarterMail/MailService/Data/Converters/DomainConverter.cs:line 76
[2024.06.14] 03:56:09.821 [domain1.com] Conversion finished in 0 seconds.

• Does the migration process seems correct to you ? Are there some stuff to be aware that I maybe missed ?
• It looks like the web interface is a bit slower on the Linux VM, for example listing domains takes 4-5 seconds while it's quite instant on the windows VM. I thought it was the NFS mount which is was slowing this down, but I did a test copying the domains files locally and it's almost the same speed for listing domains.