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.

COPYRIGHT

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.