PMDAXFS(1)

💅 PMDAXFS(1) — the XFS filesystem performance metrics domain agent (PMDA) ✨

okay bestie, welcome to the pmdaxfs page, it lives in the General Commands Manual section and it's honestly so iconic once you get it 🫶

---

🌸 SYNOPSIS 🌸

$PCP_PMDAS_DIR/xfs/pmdaxfs [-D debug] [-d domain] [-l logfile]

that's the whole vibe. three little optional flags. slay.

---

🦋 DESCRIPTION 🦋

pmdaxfs is a Performance Metrics Domain Agent (PMDA — yes it's an acronym, iykyk) and what it does is extract performance metrics that describe the state of the XFS filesystem straight out of the Linux kernel. no cap, that's the job. 💖

so the xfs PMDA exports metrics that measure info about all of this:

• metadata buffer usage
• the journal
• btree operations
• inode operations
• extended attributes
• directories
• quotas
• read and write operation counts
• and of course... throughput 👑

and here's a lil treat: the PMDA gives you a facility to reset the values of all counters to zero, using pmstore(1) with the xfs.control.reset metric. reset era fr fr. 🔄

okay so a brief rundown of the pmdaxfs command line options, here we go:

• -d — this one is absolutely crucial bestie, listen. the performance metrics domain number you put here must be unique and consistent. meaning: domain should be different for every PMDA on the one host, and the same domain number should be used for the same PMDA on all hosts. it's giving "same energy everywhere, no duplicates locally". 💀
• -l — where the log file lives. by default a log file named xfs.log gets written in the current directory of pmcd(1) when pmdaxfs is started, i.e. $PCP_LOG_DIR/pmcd. but!! if the log file cannot be created or is not writable, output goes to the standard error instead. fallback queen. 🙈

---

🎀 INSTALLATION 🎀

the xfs PMDA is installed and available by default on Linux. it's just there. main character behavior.

if you wanna undo the installation (breaking up is hard, but okay), do the following as root:

# cd $PCP_PMDAS_DIR/xfs
# ./Remove

and if you wanna establish access to the names, help text and values for the XFS performance metrics once more after removal (we love a comeback arc ✨), do the following as root:

# cd $PCP_PMDAS_DIR/xfs
# ./Install

heads up bestie: pmdaxfs is launched by pmcd(1) and should never be executed directly. the Install and Remove scripts notify pmcd(1) when the agent is installed or removed, so they handle the whole thing for you. let them cook. 🍓

---

💜 FILES 💜

• $PCP_PMCDCONF_PATH — command line options used to launch pmdaxfs
• $PCP_PMDAS_DIR/xfs/help — default help text file for the xfs metrics
• $PCP_PMDAS_DIR/xfs/Install — installation script for the pmdaxfs agent
• $PCP_PMDAS_DIR/xfs/Remove — undo installation script for the pmdaxfs agent
• $PCP_LOG_DIR/pmcd/xfs.log — default log file for error messages and other information from pmdaxfs

---

🌈 PCP ENVIRONMENT 🌈

environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. on each installation, the file /etc/pcp.conf contains the local values for these variables. and the $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5). very configurable, very demure. 💅

---

🔥 DEBUGGING OPTIONS 🔥

the -D or --debug option enables the output of additional diagnostics on stderr to help triage problems. though ngl, the information is sometimes cryptic and primarily intended to provide guidance for developers rather than for end-users — so if you're a regular user staring at it like 👁️👄👁️, that's expected.

debug is a comma separated list of debugging options. use pmdbg(1) with the -l option to obtain a list of the available debugging options and their meaning. go get that list bestie. 📋

---

⭐ SEE ALSO ⭐

PCPIntro(1), pmcd(1), pmstore(1), pcp.conf(5) and pcp.env(5).

---

and that's the page!! 💖 this was brought to you by Performance Co-Pilot (that's the PCP in the corner, the source/version vibe) and this whole thing is dated PMDAXFS(1) — so go forth, read your metrics, and remember: never run pmdaxfs directly, let pmcd(1) do it. periodt. 👑✨🦋