jfs_tune(8)

💖 jfs_tune — it's the jfs_tune(8) page, bestie ✨

okay so you know how sometimes you just wanna tweak your JFS file system's lil settings? yeah. that's this. jfs_tune lives in section 8 of the manual (the grown-up sysadmin section 💅).

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🌸 NAME 🌸

jfs_tune — adjust tunable file system parameters on JFS. that's it, that's the whole job, no cap 🎀

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🦋 SYNOPSIS 🦋

jfs_tune [options] device

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✨ DESCRIPTION ✨

so jfs_tune adjusts the tunable parameters on a Linux JFS file system or an external journal. that's the whole vibe. 🫶

real talk tho: jfs_tune must be run as root. no root, no slay. periodt.

device is the special file name corresponding to the actual device — like /dev/hdb1 for example — the one where a JFS file system or JFS external journal has been created. that's your target, your main character, your whole entire moment. 👑

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💅 OPTIONS 💅

• -J device=external-journal — attaches the JFS external journal that lives on external-journal to the JFS file system on device. it's giving "letting your bestie borrow your charger" but for journals 🔌

the external journal has to already exist first, created with this command:

mkfs.jfs -J journal_dev external-journal

and yeah, more than one file system can share the same external journal — it's generous like that, it's a sharer, we love her. 💖

attach that external journal to the file system with:

jfs_tune -J device=external-journal device

instead of naming a device directly, external-journal can also be specified as either LABEL=label or UUID=UUID. (and psst — use jfs_tune -l device to display a journal device's volume label and UUID, iykyk 😌)

• -l — lists the contents of the JFS file system or external journal superblock that resides on device. it's a little peek behind the curtain, a vibe check on your superblock 🌈
• -L volume-label — sets the volume label of the JFS file system or external journal. heads up bestie: JFS labels can be at most 16 characters long. if volume-label is longer than 16 characters, jfs_tune will truncate it and print a warning. 💀 (she said "that's enough of that")

the volume label can be used by mount(8), fsck(8), and /etc/fstab(5) (and possibly others) by specifying LABEL=volume_label instead of a block special device name like /dev/hda5. so cute, so convenient. 🎀

• -U UUID — sets the universally unique identifier (UUID) of the file system or external journal device to UUID. the format is a series of hex digits separated by hyphens, like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16". iconic string honestly.

the UUID parameter may also be one of the following:

• clear — clear the file system UUID 🧼
• random — generate a new randomly-generated UUID 🎲
• time — generate a new time-based UUID ⏰

the UUID may be used by mount(8), fsck(8), and /etc/fstab(5) (and possibly others) by specifying UUID=uuid instead of a block special device name like /dev/hda1.

see uuidgen(8) for more information. 🦋

• -V — prints version information and exits (regardless of any other chosen options). she said "I'm leaving, I don't care what else you asked for." 😭💅

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🔥 EXAMPLES 🔥

setting a randomly-generated UUID for the JFS file system on the 3rd partition of the 2nd hard disk, and viewing the resultant superblock:

jfs_tune -l -U random /dev/hdb3

attaching an already existing external journal on a device labeled JFSLog to a JFS file system on /dev/hda8:

jfs_tune -J device=LABEL=JFSLog /dev/hda8

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🙈 REPORTING BUGS 🙈

if you find a bug in JFS or jfs_tune, please report it via the bug tracking system (the "Report Bugs" section) of the JFS project web site: http://jfs.sourceforge.net/

and please send as much pertinent information as possible, including any error messages resulting from running jfs_tune. the more tea, the better 🍓

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👑 SEE ALSO 👑

jfs_fsck(8), jfs_mkfs(8), jfs_fscklog(8), jfs_logdump(8), jfs_debugfs(8)

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💜 AUTHOR 💜

Barry Arndt (barndt@us.ibm.com) 🌟

jfs_tune is maintained by IBM. see the JFS project web site for more details: http://jfs.sourceforge.net/

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and that's the whole page, bestie!! this version of the page is from October 28, 2002 (the JFS project's own, no cap) — go forth and tune responsibly, mwah 💋✨