Re: [reiserfs-dev] Results of testing Reiserfs on large block devices.

[Hans Reiser <reiser@namesys.com>]

Peter Chubb wrote:

>Hi folks,
>   I couldn't get Reiserfs to work on large devices.  I've tracked the
>problem down.
>
>  When Reiserfs is mounted, it tries to allocate a chunk of memory for
>bitmaps using kmalloc.  The largest chunk allocatable by kmalloc is
>128k.  This limits the size of a reiserfs to just under 2TB on a
>64-bit platform (16384 bitmaps times 8bytes per pointer) or just under
>4TB on a 32 bit platform (32768 bitmaps times 4bytes per pointer).
>
>This reasoning assumes that the number of bitmaps is given by the
>formula (number_of_blocks + (8 * blocksize - 1))/(8 * blocksize) where
>blocksize is 4096 bytes.  Thus 
>	  number_of_blocks = 8 * 4096 * (16384 - 1) - 1  [64 bit]
>								
>	  number_of_blocks = 8 * 4096 * (32768 - 1) - 1  [32 bit]
>
>Hacking mm/slab.c to increase the memory limit allowed larger
>filesystems to be mounted, but I haven't tested these thoroughly yet.
>--
>Dr Peter Chubb				    peterc@gelato.unsw.edu.au
>You are lost in a maze of BitKeeper repositories, all almost the same.
>
>
>
>  
>
Thanks for figuring this out.  Oleg will fix it.

-- 
Hans