fail: doveadm backup -s "<state>" with a huuge number of mailboxes

Timo Sirainen tss at
Thu Nov 12 22:12:21 UTC 2015

On 12 Nov 2015, at 12:56, Heiko Schlittermann <hs at> wrote:
> Hello,
> I'm using 2.2.13.
> For syncing I'm using repetitions of about the
> following (simplified for readability):
>    state_file=.s
>    doveadm \
>        -o imapc_master_user=<master> \
>        -o imapc_password=<pw>      \
>        -o imapc_host=<host>        \
>        -o mail_fsync=never         \
>        backup -s "$(<.s)" -u "<user>" -R imapc: >.s_new
>    mv .s_new .s
> The user has about 4501 IMAP folders. This makes a huge
> state output of about 128 kB. This in turn leads to an overly long
> command line in the next iteration. (excuse: command line too long)
> Is there any chance to solve this? I think, the only possibility would
> be to have doveadm-backup -s read the state from a *file*, wouldn't it?

Right now no way to read it from a file. But is this Linux? I thought Linux had unlimited (or at least very large) command line length nowadays.

More information about the dovecot mailing list