GCONCAT(8)

💅 GCONCAT(8) — the manual page, but make it make sense

okay bestie, so this is gconcat(8), and it lives in the System Manager's Manual. It's the disk concatenation control utility, and honestly it's giving "let's glue a bunch of disks together and pretend it's one big one" energy. Come sit, I'll walk you through it. 🫶

✨ NAME ✨

gconcat — the disk concatenation control utility. that's it, that's the whole vibe.

🌸 SYNOPSIS 🌸

gconcat create [-v] name prov ...
gconcat destroy [-fv] name ...
gconcat label [-hv] name prov ...
gconcat append [-hv] name prov
gconcat stop [-fv] name ...
gconcat clear [-v] prov ...
gconcat dump prov ...
gconcat list
gconcat status
gconcat load
gconcat unload

💖 DESCRIPTION 💖

The gconcat utility is used for device concatenation configuration. And there are, like, two whole methods for setting that up — pick your fighter:

• "manual" — no metadata are stored on the devices. So the concatenated device has to be configured by hand every single time it is needed. every time. it's giving high-maintenance 💀
• "automatic" — uses on-disk metadata to detect devices. Once devices are labeled, they will be automatically detected and configured. slay, it just works ✨

The first argument to gconcat indicates an action to be performed:

• create — Concatenate the given devices with specified name. This is the "manual" method. The kernel module geom_concat.ko will be loaded if it is not loaded already.
• label — Concatenate the given devices with the specified name. This is the "automatic" method, where metadata are stored in every device's last sector. The kernel module geom_concat.ko will be loaded if it is not loaded already.

Additional options include:

• -h — Hardcode providers' names in metadata.

• append — Append a new device to the end of an existing concatenate device with the specified name.

If the existing device is using the "manual" method, the new device is simply appended as-is.

If the existing device is using the "automatic" method, the device is appended persistently. New gconcat metadata is written to all existing components, as well as to the newly added one. lowkey iconic behavior ngl 🎀

Additional options include:

• -h — Hardcode providers' names in metadata.

• stop — Turn off existing concatenate device by its name. This command does not touch on-disk metadata! ⚠️

Additional options include:

• -f — Stop the given device even if it is opened.

• destroy — Same as stop. (yes bestie, literally the same thing, they're twins 💅)
• clear — Clear metadata on the given devices.
• dump — Dump metadata stored on the given devices.
• list — See geom(8).
• status — See geom(8).
• load — See geom(8).
• unload — See geom(8).

Additional options:

• -v — Be more verbose. (she talks more. we love her for it 🗣️)

🦋 SYSCTL VARIABLES 🦋

The following sysctl(8) variables can be used to control the behavior of the CONCAT GEOM class. The default value is shown next to each variable.

kern.geom.concat.debug: 0

Debug level of the CONCAT GEOM class. This can be set to a number between 0 and 3 inclusive. If set to 0 minimal debug information is printed, and if set to 3 the maximum amount of debug information is printed. so like, dial it up only if you're ready for the full lore dump 🔥

⭐ EXIT STATUS ⭐

Exit status is 0 on success, and 1 if the command fails. no in-between, she's decisive 💅

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🌈 EXAMPLES 🌈

The following example shows how to configure four disks for automatic concatenation, create a file system on it, and mount it:

gconcat label -v data /dev/da0 /dev/da1 /dev/da2 /dev/da3
newfs /dev/concat/data
mount /dev/concat/data /mnt
[...]
umount /mnt
gconcat stop data
gconcat unload

Configure concatenated provider on one disk only. Create file system. Add two more disks and extend existing file system. glow-up arc fr fr 🧚

gconcat label data /dev/da0
newfs /dev/concat/data
gconcat label data /dev/da0 /dev/da1 /dev/da2
growfs /dev/concat/data

🎀 SEE ALSO 🎀

geom(4), loader.conf(5), geom(8), growfs(8), mount(8), newfs(8), sysctl(8), umount(8)

💜 HISTORY 💜

The gconcat utility appeared in FreeBSD 5.3. a classic, an OG, a main character 👑

👑 AUTHORS 👑

Pawel Jakub Dawidek <pjd@FreeBSD.org> — ty for your service, king 🫡

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okay that's the whole page!! and just so we're official and everything: this one's from the Debian manual set, dated January 23, 2025 — mwah, take care of her 💖✨