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

[Jeff Garzik]

Laurent Vivier wrote:
> Jeff Garzik wrote:
> > Laurent Vivier wrote:
> > > 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.
> > That doesn't solve anything, if you are not using a 64bit filesystem.
>
> Sorry, I don't undestand why ???
>
> You can use 32bit filesystem too, but you limit the size of the logical volume
> to be compatible with the filesystem you use. LVM allows to create several 32bit
> volumes on a big (> 8T) disk (if exists)

Let's review the thread:

qiyong: <these limits> exist in the filesystem
you: bust those limits with LVM!

I think you are misunderstanding the subthread.


> > > "partitioning is obsolete" ;-)
> > LVM is nothing but a partition manager...
>
> LVM is more than a partition manager:

I am well aware of what LVM2 and device mapper can do.

	Jeff



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