Hello.
 
We are running dovecot 2.3.13. Full doveconf -n output below
 
In 2.3.14 Changelog I found this:
 
* Remove XZ/LZMA write support. Read support will be removed in future release.
 
We are using mdbox + XZ/LZMA for alternate storage (messages older than 2 weeks are moved to ALT storage via cron job), so we must convert from XZ to another thing (maybe zstd or bz2).
 
Our cron job script:
 
/usr/bin/doveadm  -o mdbox_rotate_interval=14d -o mdbox_purge_preserve_alt=no -o mdbox_rotate_size=250m -o zlib_save=xz -o zlib_save_level=9 altmove -u $user
 
 
My first try to accomplish this conversion, without downtime, is this
 
* Pick an user
* Move all ALT messages from that user mailbox to MAIN storage location (doveadm altmove -r)
* Use doveadm altmove with zstd to recompress messages to ALT
 
 
I have picked an user, and tried this:
 
 /usr/bin/doveadm altmove -r -u myuser all
 
 
But it did not work. I expected with that command to move ALL messages from ALT storage to main storage, but 0 messages moved, checked with du -ksh
 
What is the proper way to recompress messages in ALT storage in mdbox?
 
doveconf -n output:
 
 
auth_cache_negative_ttl = 10 secs
auth_cache_size = 10 M
auth_cache_ttl = 2 mins
auth_master_user_separator = *
auth_worker_max_count = 5500
base_dir = /var/run/dovecot/
default_client_limit = 5000
default_process_limit = 6500
disable_plaintext_auth = no
imap_capability = +XLIST
imap_client_workarounds = tb-extra-mailbox-sep delay-newmail tb-lsub-flags
imap_id_log = *
imap_max_line_length = 92 k
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
mail_fsync = never
mail_gid = entrega
mail_home = /buzones_primarios/%2.26Hn/%2.200Hn/%n/home_usuario
mail_location = mdbox:/buzones_primarios/%2.26Hn/%2.200Hn/%n:ALT=/buzones_secundarios/%2.26Hn/%2.200Hn/%n:INDEX=/indices_correo/%2.26Hn/%2.200Hn/%n:ITERINDEX
mail_log_prefix = "%s(%u)<%{session}>: "
mail_max_userip_connections = 2500
mail_plugins = " zlib acl quota virtual"
mail_uid = entrega
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date
mdbox_rotate_interval = 1 days
mdbox_rotate_size = 60 M
namespace {
  inbox = yes
  location =
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox SPAM {
    auto = subscribe
    special_use = \Junk
  }
  mailbox Sent {
    auto = subscribe
    special_use = \Sent
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = /etc/dovecot/deny
  deny = yes
  driver = passwd-file
}
passdb {
  args = /etc/dovecot/dovecot-ldap.conf
  driver = ldap
}
passdb {
  args = /etc/usuario_maestro.txt
  driver = passwd-file
  master = yes
}
passdb {
  args = /etc/dovecot/dovecot-ldap.conf
  driver = ldap
}
plugin {
  acl = vfile
  lda_mailbox_autosubscribe = yes
  quota = dict:Cuota de usuario::file:/indices_correo/cuotas/%n
  quota_rule2 = Trash:storage=+10%%
  quota_warning = storage=90%% aviso_cuota 90 %u
  sieve = /buzones_primarios/%2.26Hn/%2.200Hn/%n/home_usuario/dovecot.sieve
  sieve_dir = /buzones_primarios/%2.26Hn/%2.200Hn/%n/home_usuario/sieve/
  sieve_max_redirects = 20
  zlib_save = gz
  zlib_save_level = 1
}
pop3_no_flag_updates = yes
protocols = pop3 imap sieve
service anvil {
  client_limit = 25000
}
service auth {
  client_limit = 32000
  unix_listener auth-master {
    user = entrega
  }
  unix_listener auth-userdb {
    user = entrega
  }
  user = root
}
service aviso_cuota {
  executable = script /usr/local/bin/quota-warning.sh
  unix_listener aviso_cuota {
    mode = 0666
  }
  user = entrega
}
service config {
  process_min_avail = 4
}
service imap-login {
  executable = /usr/libexec/dovecot/imap-login
  group = dovenull
  process_min_avail = 2
  service_count = 0
  vsz_limit = 1 G
}
service imap {
  executable = /usr/libexec/dovecot/imap
  process_limit = 8000
  process_min_avail = 12
  vsz_limit = 1 G
}
service managesieve-login {
  executable = /usr/libexec/dovecot/managesieve-login
  inet_listener sieve {
    port = 2000
  }
  process_limit = 2000
  vsz_limit = 1 G
}
service managesieve {
  executable = /usr/libexec/dovecot/managesieve
  process_limit = 5000
}
service pop3-login {
  executable = /usr/libexec/dovecot/pop3-login
  process_limit = 5000
  process_min_avail = 2
  service_count = 0
  vsz_limit = 1 G
}
service pop3 {
  executable = /usr/libexec/dovecot/pop3
  process_limit = 5000
}
service stats {
  fifo_listener stats-mail {
    mode = 0600
    user = entrega
  }
}
ssl_ca = </etc/pki/tls/certificado_europa_2020/CadenaCompletaCA3.crt
ssl_cert = </etc/pki/tls/certificado_europa_2020/full_chain.pem
ssl_cipher_list = ECDHE-RSA-AES128-SHA256:AES128-GCM-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
userdb {
  args = /etc/dovecot/dovecot-ldap.conf
  driver = ldap
}
userdb {
  args = /etc/dovecot/dovecot-ldap-userdb.conf
  driver = ldap
}
verbose_proctitle = yes
protocol sieve {
  managesieve_implementation_string = dovecot
  managesieve_logout_format = bytes=%i/%o
  managesieve_max_line_length = 64 k
}
protocol lda {
  hostname = XXXX
  info_log_path =
  log_path =
  mail_fsync = optimized
  mail_plugins = sieve zlib quota virtual
  postmaster_address = correo@XXXX
  syslog_facility = mail
}
protocol imap {
  mail_plugins = zlib quota imap_quota virtual
}
protocol pop3 {
  mail_plugins = zlib quota virtual
  pop3_enable_last = yes
  pop3_uidl_format = %g
}