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Re: [linux-lvm] Possible to raise Max LV?



On Tue, Feb 27, 2001 at 03:04:17PM -0600, Eric M. Hopper wrote:
> On Tue, Feb 27, 2001 at 01:55:05PM -0700, Andreas Dilger wrote:
> > Ragnar Kj_rstad writes:
> > > What about increesing the [PE size] default, to say 32 MB?
> > > 32 MB should be enough for everyone (because of the 2TB limit), and 16
> > > MB waste on every PV isn't that bad.
> > 
> > So says the guy from a company called "Big Storage" ;-).  However,
> > I've seen several people who make multiple partitions on a single
> > disk, and then turn these into PVs (don't ask me why), so they would
> > be wasting 16MB per partition.  Most people will not need 2TB LVs for
> > some time to come.  However, if your systems usually have large LVs,
> > then it is OK for you to increase the default for your systems.
> 
> 	I actually intend to for mine sometime later because it reduces
> the fragmentation problem.  I know it shouldn't be that big a deal with
> 4M PEs, but with 32M PEs it'll be even less of a deal.  :-)
> 
> 	I actually thinking of generally scaling my PEs to around 0.1%
> of my total available space on the theory that allocation of finer
> grained chunks than that is kinda silly.
> 
> 	If I weren't working on some stuff of my own, I'd dive in and
> see if I could write a defrag utility for LVM.  The part I'm not sure
> how I'd handle would be striped LVs.
> 
> Have fun (if at all possible),
> -- 

As Andreas already pointed out: 4M basically is a good value to keep
the overhead small.

As I stated in another email: the ~64k extents per LV limit will likely
disappear in the future (no date though ;-).
For now you *need* to plan for the maximum LV size you want to create/extend to
during planning of the VG(s). 2T is the Linux limit per block device anyway
at least until Linux 2.5 changes that.

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen Sistina com                           +49 2626 141200
                                                       FAX 924446
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