Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3

[Laurent Vivier]

Qi Yong wrote:
> Linus Torvalds wrote:
> 
>> On Fri, 9 Jun 2006, Stephen C. Tweedie wrote:
>>  
>>
>>> When is the Linux syscall interface enough?  When should we just bump it
>>> and cut out all the compatibility interfaces?
>>>
>>> No, we don't; we let people configure certain obsolete bits out (a.out
>>> support etc), but we keep it in the tree despite the indirection cost to
>>> maintain multiple interfaces etc.
>>>    
>>>
>> Right. WE ADD NEW SYSTEM CALLS. WE DO NOT EXTEND THE OLD ONES IN WAYS THAT 
>> MIGHT BREAK OLD USERS.
>>
>> Your point was exactly what?
>>
>> Btw, where did that 2TB limit number come from? Afaik, it should be 16TB 
>> for a 4kB filesystem, no?
>>  
>>
> 
> Partition tables describe partitions in units of one sector.
> 2^(32+9) = 2T
> 
> To prevent integer overflow, we should use only 31 bits of a 32-bit integer.
> 2^(31+12) = 8T
> 
> There's _terrible_ hacks to really get to 16T.
> 
> -- qiyong
> 

IMHO, a simple solution is to use "Logical Volume Manager" instead of partition
manager: we create 64bit filesystem in a Logical Volume, not in a partition.

"partitioning is obsolete" ;-)

Regards,
Laurent

-- 
Laurent Vivier
Bull, Architect of an Open World (TM)
http://www.bullopensource.org/ext4

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