[Bug 1045178] Re: btrfs core image too large for minimal MBRs

[Colin Watson]

axion, this is probably going to be very hard for us to fix and is not
going to be a priority, as btrfs is a complex filesystem that requires
considerable amounts of code in GRUB to read.  Given that btrfs is known
not to be terribly space-efficient in many cases, it seems an odd
decision to use btrfs on a small drive and then skimp on space for the
boot loader code required to read it.  I would expect that the megabyte
you'd spend on modern partition alignment (which, incidentally, will
perform much better on SSDs than the old-style alignment - many of them
really benefit from being aligned on 1024*1024-byte boundaries, or
sometimes even larger) will be dwarfed by the space you'll lose to
btrfs.  So why worry about the pennies when you're already not worrying
about pounds?

Besides, you have an 80GB drive here - a megabyte is not going to break
the bank!  I use an 80GB SSD myself and it is not a problem.

I recommend one or more of the following:

 * Align the first partition to a multiple of 1024*1024 bytes.  Yes, really.  It will be better.
 * Use a separate ext2 /boot partition if you absolutely must have minimal space in the MBR.

** Changed in: grub2 (Ubuntu)
       Status: Confirmed => Triaged

** Changed in: grub2 (Ubuntu)
   Importance: Undecided => Low

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https://bugs.launchpad.net/bugs/1045178

Title:
  btrfs core image too large for minimal MBRs

Status in “grub2” package in Ubuntu:
  Triaged

Bug description:
  Grub install failed at clean install. core.img too large to fit into
  64 sectors ( 32Kb )

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: ubiquity 2.11.18
  ProcVersionSignature: Ubuntu 3.5.0-6.6-generic 3.5.0
  Uname: Linux 3.5.0-6-generic i686
  ApportVersion: 2.4-0ubuntu5
  Architecture: i386
  CasperVersion: 1.320
  Date: Mon Sep  3 07:48:03 2012
  InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
  LiveMediaBuild: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120724.2)
  ProcEnviron:
   LANGUAGE=en_US.UTF-8
   TERM=linux
   PATH=(custom, no user)
   LANG=en_US.UTF-8
  SourcePackage: grub-installer
  UpgradeStatus: No upgrade log present (probably fresh install)

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