CMOGSTORED(1) User Commands CMOGSTORED(1)

NAME
cmogstored - manual page for cmogstored 1.8.1

SYNOPSIS
cmogstored [OPTION...]

DESCRIPTION
cmogstored -- alternative mogstored implementation for MogileFS

--config=<file>
Set config file (no default, unlike mogstored)

-d, --daemonize
Daemonize

--docroot=<path>
Docroot above device mount points. Defaults to /var/mogdata

--httplisten=<ip:port> IP/Port HTTP server listens on

--maxconns=<number>
Number of simultaneous clients to serve. Default 10000

--mgmtlisten=<ip:port> IP/Port management/sidechannel listens on

--pidfile=<path>
path to PID file

-?, --help
give this help list

--usage
give a short usage message

-V, --version
print program version

SIGNALS
SIGQUIT - gracefully shutdown the server

SIGUSR2 - upgrade executable on the fly

UPGRADING
Upgrading cmogstored on-the-fly is possible since version 1.2.0. The
procedure is close to the one used by nginx users: send SIGUSR2
followed by SIGQUIT to the old process. Use of SIGWINCH and SIGHUP are
currently not supported (but may be in the future). Procedures for the
nginx upgrade are documented here:
https://www.nginx.com/resources/wiki/start/topics/tutorials/commandline/#upgrading-
to-a-new-binary-on-the-fly

USAGE FILES
Like Perl mogstored(1), cmogstored writes "devNNN/usage" files for
mogilefsd(1) instances to monitor disk space utilization.

As of cmogstored 1.7, this information is stored in-memory in case the
device becomes too full to write the usage file. Users may choose to
make usage files unwritable (via "chmod 000") to reduce disk wear on
otherwise read-mostly devices.

As of cmogstored 1.8, the in-memory representation of these usage files
is updated by PUT and DELETE HTTP requests in case write traffic is too
high for periodic (10s) updates.

MALLOC TUNING
malloc(3) implementations tuned for multithreading speed (and not
memory usage) may cause large amounts of metadata overhead in
infrequently-used arenas. While cmogstored may use many threads for
filesystem I/O, cmogstored is designed to not be dependent on malloc(3)
performance nor scalability.

On GNU/Linux systems with glibc, we recommend setting MALLOC_ARENA_TEST
and MALLOC_ARENA_MAX to low numbers to limit the number arenas.
Setting the value of each to 1 or 2 should be enough, even.

ENVIRONMENT
MOG_IOSTAT_CMD - command-line for invoking iostat(1). This is used by
the sidechannel to report disk utilization to trackers. Default:
"iostat -dx 1 30"

LISTEN_FDS, LISTEN_PID - may be used for systemd-style socket
activation regardless of whether systemd is on the system. See
sd_listen_fds(3) for more information. Since cmogstored supports two
protocols on different sockets, the command line or config file must
still specify which addresses to listen on. This feature is available
in cmogstored 1.5.0 and later.

CMOGSTORED_FD - a comma-delimited list of integer file descriptors.
This is used internally for SIGUSR2 upgrades, but may be specified at
startup (e.g. via env(1)) as it is not tied to LISTEN_PID like
LISTEN_FDS is. Unlike LISTEN_FDS, CMOGSTORED_FD does not rely on
inherited file descriptors being contiguous.

See MALLOC TUNING for environment variables which may affect memory
usage.

REPORTING BUGS
Only bug reports in plain-text email will be read.

Please email to either the public inbox at (no subscription required):

<cmogstored-public@yhbt.net>

(archived at <https://yhbt.net/cmogstored-public/>)

or the public MogileFS mailing list (subscription required)

<mogile@googlegroups.com>

(archived at <https://groups.google.com/forum/#!forum/mogile>).

Report bugs to cmogstored-public@yhbt.net.

License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>. This is
free software: you are free to change and redistribute it. There is NO
WARRANTY, to the extent permitted by law.

SEE ALSO
cmogstored website: https://yhbt.net/cmogstored/README You can learn
more about MogileFS at https://github.com/mogilefs/MogileFS-Server

cmogstored source code is available via git:

git clone https://yhbt.net/cmogstored.git

cmogstored 1.8.1 February 2021 CMOGSTORED(1)