Re: Help with space

[Roman Mamedov <rm@romanrm.net>]

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On Fri, 28 Feb 2014 07:27:06 +0000 (UTC)
Duncan <1i5t5.duncan@cox.net> wrote:

> Based on what I've read on-list, btrfs is not arch-agnostic, with certain 
> on-disk sizes set to native kernel page size, etc, so a filesystem 
> created on one arch may well not work on another.
> 
> Question: Does this apply to x86/amd64?  Will a filesystem created/used 
> on 32-bit x86 even mount/work on 64-bit amd64/x86_64, or does upgrading 
> to 64-bit imply backing up (in this case) double-digit TiB of data to 
> something other than btrfs and testing it, doing a mkfs on the original 
> filesystem once in 64-bit mode, and restoring all that data from backup?

Page size (4K) is the same on both i386 and amd64. It's also the same on ARM.

Problem arises only on architectures like MIPS and PowerPC, some variants of
which use 16K or 64K page sizes.

Other than this page size issue, it has no arch-specific dependencies,  e.g.
no on-disk structures with "CPU-native integer" sized fields etc, that'd be too
crazy to be true.

-- 
With respect,
Roman

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