RBD-NBD(8)

💖 RBD-NBD 💖

okay bestie, welcome to rbd-nbd — it's a manual page, it's from Ceph, and it's about to map your rbd images onto nbd devices. yes, the man page is literally named rbd-nbd and lives in the Ceph manual. sit down, hydrate, let's go 🫶

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✨ NAME ✨

rbd-nbd — map rbd images to nbd device

like. that's the whole job. that's the vibe. 💅

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🌸 SYNOPSIS 🌸

rbd-nbd [-c conf] [--read-only] [--device nbd device] [--snap-id snap-id] [--nbds_max limit] [--max_part limit] [--exclusive] [--notrim] [--encryption-format format] [--encryption-passphrase-file passphrase-file] [--io-timeout seconds] [--reattach-timeout seconds] map image-spec | snap-spec
rbd-nbd unmap nbd device | image-spec | snap-spec
rbd-nbd list-mapped
rbd-nbd attach --device nbd device image-spec | snap-spec
rbd-nbd detach nbd device | image-spec | snap-spec

five little lines, five whole moods, and honestly? iconic. ✨

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🦋 DESCRIPTION 🦋

so rbd-nbd is a client for RADOS block device (rbd) images, basically the same energy as the rbd kernel module. it will map a rbd image to a nbd (Network Block Device) device, which lets you access it as a regular local block device. local block device. YOUR block device. main character energy fr fr. 👑

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💅 OPTIONS 💅

• -c ceph.conf — use this ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to figure out monitor addresses during startup. yes, a different conf, a different life.
• --read-only — map read-only. no writing, bestie, this one's just for looking respectfully. 👀
• --nbds_max limit — override the parameter nbds_max of the NBD kernel module when modprobe happens; it's used to limit the count of nbd device.
• --max_part limit — override for module param max_part.
• --exclusive — forbid writes by other clients. gatekeeping, but make it infrastructure. 🔒
• --notrim — turn off trim/discard.
• --encryption-format — image encryption format. possible values: luks, luks1, luks2. pick your fighter.
• --encryption-passphrase-file — path of file containing a passphrase for unlocking image encryption. keep it secret, keep it safe. 🤫
• --io-timeout seconds — override device timeout. the Linux kernel will default to a 30 second request timeout, but this lets you optionally specify an alternate timeout. customize your patience level, love that for you.
• --reattach-timeout seconds — specify timeout for the kernel to wait for a new rbd-nbd process to be attached after the old process is detached. the default is 30 second.
• --snap-id snapid — specify a snapshot to map/unmap/attach/detach by ID instead of by name. numbers only, no name-calling. 😌

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🎀 IMAGE AND SNAP SPECS 🎀

so here's how you spell things around here:

• image-spec is [pool-name]/image-name
• snap-spec is [pool-name]/image-name@snap-name

the default for pool-name is "rbd". but lowkey important: if an image name contains a slash character ('/'), the pool-name is required. yes, required. don't skip it. 🙈

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🌈 AVAILABILITY 🌈

rbd-nbd is part of Ceph, a massively scalable, open-source, distributed storage system. please refer to the Ceph documentation at <https://docs.ceph.com/> for more information. go read the docs, bestie, they ate. 📚✨

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👑 SEE ALSO 👑

• rbd(8)

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💜 Copyright 💜

2010-2014, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)

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and that's the whole page, bestie 🥹 this one came from dev, dated Oct 06, 2026, and it's RBD-NBD(8) — that's a wrap, mwah 💋✨