GFMDHOST(1)

📦 version 2.7.20, in debian bookworm, debian trixie, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

✨ NAME ✨

gfmdhost — the Gfarm metadata server host maintenance command 💅

okay so bestie, you found it: this is GFMDHOST(1) from the Gfarm manual, and it is literally your group-chat-verified tool for wrangling metadata server hosts. no cap. 🫶

🦋 SYNOPSIS 🦋

gfmdhost [-l] [-P path] [-1]

gfmdhost [-N] [-P path] [-1]

gfmdhost {-c | -m} [-P path] [-1] [-p port-number] [-C cluster-name]
         [-t {m | c | s}] {metadata-server-name}

gfmdhost {-d} [-P path] [-1] {metadata-server-name}

🌸 DESCRIPTION 🌸

gfmdhost is your girl for displaying and maintaining all the info about synchronous and asynchronous replicated metadata servers. she's giving full maintenance-command energy. 👑

she comes with a few functions, and you pick one with -l, -c, -m and -d. these functions are mutually exclusive — like, only ONE of them at a time, pick your fighter. and if you specify none of them? then she just lists the registered metadata server (gfmd host) names for you. simple. iconic. ✨

🌈 FUNCTIONS 🌈

here's the whole roster, bestie:

💫 <none>

if you don't specify any function, all the registered gfmd hosts get displayed in alphabetical order. clean, sorted, no drama. 🎀

💫 -l

all registered gfmd hosts are listed with detailed information. they're grouped by their clusters and ordered alphabetically. yes queen, organized.

the detailed information is displayed in the following order:

  • Connection State (+|||-|?|x|e|u) — okay this one has LORE, listen up:
    • + means the gfmd is connected to the master gfmd and its metadata are synchronized. 💚
    • | means the gfmd is connected to the master gfmd, but its metadata have not been synchronized yet. note that this may happen even on a synchronous slave gfmd, when the slave is just connecting to the master, or in the middle of metadata transfer even if it has been already synchronized. it's not a vibe, it's just timing.
    • - means the gfmd is not connected to the master gfmd.
    • ? means either the gfmd state is unknown because it's just after the connection was established, or the master gfmd is Gfarm-2.5.0, but this gfmdhost command is 2.5.1 or later. (version mismatch moment 😭)
    • x means the connection with master gfmd was established, but automatic synchronization was impossible because of too many metadata changes, so manual synchronization via dump and restore of the backend database is necessary. (that's a whole situation.)
    • e means an error happened, and the log file must be checked manually. 🙈
    • in the case of x or e, it may be displayed even when the slave gfmd is down.
    • u means the slave gfmd is connected to the master gfmd, but the state is not supported by this gfmdhost command. (she doesn't know her 💀)
    • this column for the master gfmd is always +. always. no exceptions.
  • Server Type (master|slave) — tells you whether the gfmd is master or slave. main character or supporting cast, basically. 👑
  • Replication Type (sync|async|-) — sync means a synchronous replication. async means an asynchronous replication. this column for the master is always -.
  • Configuration of Master Candidate (c|m|s) — m means the default master gfmd, c means a master candidate that can be selected as a master gfmd, and s means a gfmd that is not a master candidate and only works for a slave gfmd.
  • Cluster Name — a cluster name where the gfmd belongs to. (default) is displayed for the default cluster. 🏠

💫 -N

displays a hostname and port number of the connected metadata server. short, sweet, informative. 💅

💫 -c

registers the gfmd host that is specified in the argument. -C, -p, -t can be optionally specified. ✨

💫 -m

modifies the gfmd host that is specified in the argument. -C, -p, -t can be optionally specified. ✨

💫 -d

deletes the gfmd host that is specified in the argument. the master gfmd cannot be deleted. 🚫 like, do not even try, bestie.

💫 -?

prints usage. your emergency help button. 🆘

💅 OPTIONS 💅

  • -C cluster-name — this option specifies a cluster name where the gfmd host belongs to. if it's not specified, the default cluster is assumed. this option is only available with -c or -m option.

the cluster name means a group of synchronous replicated metadata servers. that is, slave metadata servers in the same cluster with the master metadata server are synchronously replicated servers that can be changed to a master metadata server without any loss of metadata operations. other metadata servers are asynchronously replicated servers. iykyk. 🧚

  • -p port-number — this option specifies a port number of the gfmd. if it's not specified, 601 is assumed. this option is only available with -c or -m option.
  • -t {m|c|s} — this option specifies a configuration of master candidate. it is only available with -c or -m option. m means the default master, c means a master candidate and s means a slave only gfmd. if it's not specified, c is assumed.
⚠️ the gfmd configured as the default master cannot be changed to a master candidate or slave-only directly. and if the gfmd that is not the default master is changed to the default master by -t m, the original default master is changed to a master candidate at the same time. (plot twist, but make it replication. 😭)
  • -P path — this option specifies a pathname or a Gfarm URL to identify a metadata server which will be accessed by this command. if not specified, / is used as the default value.
  • -1 — with this option, gfmdhost only tries to connect with one metadata server specified by -P option, or if missing, metadb_server_host statement in gfarm2.conf file. one server, one shot. 🎯

🎀 SEE ALSO 🎀

and that's the whole page, bestie!! this one came from the Gfarm manual and it's dated 11 March 2014 — a classic, honestly. go forth and maintain those metadata servers. slay. 👑💖✨

📦 where this page comes from