MFI(4)

📦 version 12.2, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 MFI(4) 💖

okay bestie, pull up a chair, we're talking about mfi — the LSI MegaRAID SAS driver — from the Kernel Interfaces Manual. yes this is a real manual page and yes it's about to be your new obsession. 🎀

✨ NAME ✨

mfi — LSI MegaRAID SAS driver 🦋

✨ SYNOPSIS ✨

so like, if you wanna compile this driver into the kernel (main character move), you drop these lines into your kernel configuration file:

device pci
device mfi

orrr, if you'd rather load it as a module at boot time, you put this single line into loader.conf(5):

mfi_load="YES"

and that's it. slay. 💅

✨ DESCRIPTION ✨

okay so this driver? it's for LSI's next generation PCI Express SAS RAID controllers. very demure, very mindful, very next-gen. 🌸

you get to your RAID arrays (that's the logical disks, bestie) through /dev/mfid? device nodes. and there's also a simple management interface on a per-controller basis, living at /dev/mfi?. two flavors of device node, one iconic driver. 😌

now, the tea on the name: mfi comes from the phrase "MegaRAID Firmware Interface", which is substantially different from the old "MegaRAID" interface — like, different enough that it needed a whole new driver. so if you were hoping your older SCSI and SATA MegaRAID cards would just work here? nope. 🙈 those are supported by amr(4), and they will not work with this driver. periodt.

there are two sysctls that tune how the mfi driver behaves when someone asks it to remove a mounted volume. by default the driver is like "no ❤️" and disallows any requests to remove a mounted volume. but if you set the sysctl dev.mfi.%d.delete_busy_volumes to 1, then the driver will allow mounted volumes to be removed. your call, your consequences. 💀

there's also a tunable that adjusts how the driver behaves when it's attaching to a card. by default the driver attaches to all known cards with high probe priority. but if you set the tunable hw.mfi.mrsas_enable to 1, the driver lowers its probe priority so that mrsas can attach to the card instead of mfi. sharing is caring, I guess. 🫶

and one more thing, important: mfi does not provide ATA TRIM support. refer to mrsas if TRIM support is required. not me being the bearer of bad news. 😭

✨ HARDWARE ✨

the mfi driver supports the following hardware, and honestly? the lineup ate. 👑

  • LSI MegaRAID SAS 1078
  • LSI MegaRAID SAS 8408E
  • LSI MegaRAID SAS 8480E
  • LSI MegaRAID SAS 9240
  • LSI MegaRAID SAS 9260
  • Dell PERC5
  • Dell PERC6
  • IBM ServeRAID M1015 SAS/SATA
  • IBM ServeRAID M1115 SAS/SATA
  • IBM ServeRAID M5015 SAS/SATA
  • IBM ServeRAID M5110 SAS/SATA
  • IBM ServeRAID-MR10i
  • Intel RAID Controller SRCSAS18E
  • Intel RAID Controller SROMBSAS18E

✨ FILES ✨

  • /dev/mfid? — array/logical disk interface 🍓
  • /dev/mfi? — management interface ✨

✨ DIAGNOSTICS ✨

  • mfid%d: Unable to delete busy device — an attempt was made to remove a mounted volume. yeah, that's the driver going "not today" 💀

✨ SEE ALSO ✨

amr(4), pci(4), mfiutil(8) — go read those too, iykyk 💜

✨ HISTORY ✨

the mfi driver first appeared in FreeBSD 6.1. a legend since day one, no cap. ⭐

✨ AUTHORS ✨

the mfi driver and this manual page were written by Scott Long <scottl@FreeBSD.org>. give that human their flowers. 💐

✨ BUGS ✨

the driver does not support big-endian architectures at this time. that's just how it is right now, bestie. 😭

aaaand that's the whole page! this lil slice of the Kernel Interfaces Manual came from Debian and it's dated March 13, 2019 — yeah it's been sitting there being iconic for a minute. 🎀✨ take care of your RAID arrays and hydrate!! 💖🦋

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